Colour measurement of colostrum for estimation of colostral IgG and colostrum composition in dairy cows

Instruments for on-farm determination of colostrum quality such as refractometers and densimeters are increasingly used in dairy farms. The colour of colostrum is also supposed to reflect its quality. A paler or mature milk-like colour is associated with a lower colostrum value in terms of its general composition compared with a more yellowish and darker colour. The objective of this study was to investigate the relationships between colour measurement of colostrum using the CIELAB colour space (CIE L*=from white to black, a*=from red to green, b*=from yellow to blue, chroma value G=visual perceived colourfulness) and its composition. Dairy cow colostrum samples (n=117) obtained at 4·7±1·5 h after parturition were analysed for immunoglobulin G (IgG) by ELISA and for fat, protein and lactose by infrared spectroscopy. For colour measurements, a calibrated spectrophotometer was used. At a cut-off value of 50 mg IgG/ml, colour measurement had a sensitivity of 50·0%, a specificity of 49·5%, and a negative predictive value of 87·9%. Colostral IgG concentration was not correlated with the chroma value G, but with relative lightness L*. While milk fat content showed a relationship to the parameters L*, a*, b* and G from the colour measurement, milk protein content was not correlated with a*, but with L*, b*, and G. Lactose concentration in colostrum showed only a relationship with b* and G. In conclusion, parameters of the colour measurement showed clear relationships to colostral IgG, fat, protein and lactose concentration in dairy cows. Implementation of colour measuring devices in automatic milking systems and milking parlours might be a potential instrument to access colostrum quality as well as detecting abnormal milk.

Continuous milking of dairy cows disrupts timing of peak IgG concentration appearance in mammary secretions

The length of the dry period in commercial dairy production is under close scrutiny. While the main concern is the composition and volume of milk produced, the evaluation of colostrum quality under these new paradigms has suggested a decline in IgG concentrations, while some reports indicate no change. Colostrum quality has been defined as an adequate concentration (>50 mg/ml) of immunoglobulin in the secretions to provide the newborn with maximal disease resistance. We investigated the appearance of IgG in mammary pre- and post partum secretions in cows without a dry period (continuously milked, Dry0) and compared the secretions with cows that experienced a dry period of 60 d (Dry60). Blood was collected during the experimental period and plasma analysed for progesterone (P4) and prolactin (Prl). Approximately -6 d relative to parturition, the Dry0 animals exhibited increased concentration of IgG in their secretions to an average of ∼35 mg/ml that remained rather constant through subsequent pregnancy and following parturition. Dry0 cows were producing an average IgG concentration in parturition colostrum of 44·2±17·6 mg/ml that was not different than that of controls (66·86±16·8 mg/ml). However, Dry0 cows exhibited high variation, different peak times (day) of IgG concentration including times that occurred both pre and post parturition. IgG mass of the Dry0 cows remained rather constant pre- and post partum and did not show the same declining mass following parturition that was shown for the Dry60 cows. The change in plasma P4 and Prl were shown to have no timing effect on colostrum IgG concentration.

Short communication: Immunoglobulin variation in quarter-milked colostrum

Whereas whole first-milked colostrum IgG1 variation is documented, the IgG1 difference between the quarter mammary glands of dairy animals is unknown. First colostrum was quarter-collected from healthy udders of 8 multiparous dairy cows, all within 3h of parturition. Weight of colostrum produced by individual quarters was determined and a sample of each was frozen for subsequent analysis. Immunoglobulin G1 concentration (mg/mL) was measured by ELISA and total mass (g) was calculated. Standard addition method was used to overcome colostrum matrix effects and validate the standard ELISA measures. Analysis of the data showed that cow and quarter (cow) were significantly different in both concentration and total mass per quarter. Analysis of the mean IgG1 concentration of the front and rear quarters showed that this was not different, but the large variation in individual quarters confounds the analysis. This quarter difference finding indicates that each mammary gland develops a different capacity to accumulate precolostrum IgG1, whereas the circulating hormone concentrations that induce colostrogenesis reach the 4 glands similarly. This finding also shows that the variation in quarter colostrum production is a contributor to the vast variation in first milking colostrum IgG1 content. Finally, the data suggests other factors, such as locally acting autocrine or paracrine, epigenetic, or stochasticity, in gene regulation mechanisms may impinge on colostrogenesis capacity.

Peripartal progesterone and prolactin have little effect on the rapid transport of immunoglobulin G into colostrum of dairy cows

Colostrum formation and lactogenesis in the mammary gland and the timing of parturition are regulated by endocrine signals. Changes in progesterone (P4) and prolactin (PRL) are considered key events that inhibit colostrum formation, trigger parturition, and signal the onset of lactation. The goal of our study was to determine if colostrum yield and composition and immunoglobulin transfer are affected by prepartum milking relative to the decrease in P4, peak of PRL, or occurrence of parturition. Twenty-three multiparous cows were randomly assigned to 1 of 2 groups: (1) control with first milking at 4h postcalving (CON, n=11), and (2) treatment group with first milking approximately 1d before calving and second milking at 4h after parturition (APM, n=12). Colostrum yields were recorded and proportional samples were analyzed for immunoglobulin G (IgG) concentration. Blood plasma samples for the analyses of P4 and PRL were collected 3 times daily at 8-h intervals for 4d prepartum and again taken at 4h after parturition. Total colostrum mass of APM cows was higher than that of CON cows. Immunoglobulin G concentration and protein content did not differ between antepartum milking in APM cows and postpartum milking in CON cows. Colostrum IgG concentration and protein content in APM cows at the postpartum milking were lower compared with the IgG concentration established at the prepartum (APM) and postpartum milkings of CON cows. Immunoglobulin G mass did not differ in first and second colostrum collection in APM cows but was lower compared with that of CON cows. The sum of IgG mass in APM cows (prepartum + postpartum collections) did not differ from that of CON cows. Lactose and fat in milk (concentration and mass) increased from first to second milking in APM cows. Total mass of lactose and fat in APM cows (prepartum + postpartum collections) was greater compared with that of CON cows. The finding that the time of milking relative to parturition, P4 decrease, and PRL peak slightly affected yield and quality of colostrum emphasizes the complex interactions of numerous endocrine and morphological changes occurring during colostrogenesis and lactogenesis in dairy cows. The considerably rapid transfer of immunoglobulins into colostrum of prepartum-milked cows within a few hours leads to the hypothesis that the transfer of IgG can be very fast and-contrary to earlier findings-persist at least until parturition.

Short communication: Timing of first milking affects serotonin (5-HT) concentrations

Hormonal signals differentially regulate the timing of parturition, as well lactogenesis and, potentially, colostrum formation in the mammary gland. Non-neuronal serotonin (5-HT) is a homeostatic regulator of the mammary gland. In the current study, we manipulated the timing of first milking to investigate its effects on serum 5-HT and calcium concentrations in the maternal and calf circulation, as well as in colostrum. Twenty-three cows were randomly assigned to a control (CON; n=10) group, milked for the first time at 4h postcalving, or a treatment (TRT; n=13) group, milked for the first time approximately 1 d before calving in addition to 4h postcalving. Maternal blood samples were collected for 4 d precalving, 3 times daily, and 1 blood sample was taken 4h postcalving. Calf blood samples were collected 4 (before first colostrum feeding) and 12h after birth, and at 3 wk of age. Calves from both treatments were fed colostrum from their respective mothers. Serum 5-HT concentrations were greater in CON cows and decreased significantly in TRT cows after milking was initiated precalving (951 vs. 524 ± 111 ng/mL, respectively). Cow serum calcium concentrations were affected by time, beginning to decrease 1 d precalving until 4h postcalving, but this drop in serum calcium was more pronounced in TRT cows. Serum 5-HT and calcium concentrations were negatively correlated (r=-0.57) for the CON cows and positively correlated (r=0.6) for the TRT cows. Maternal calcium and 5-HT decreased similarly due to precalving milking. Calcium and 5-HT concentrations were greater in colostrum collected from TRT cows milked precalving. Overall, calves had higher circulating 5-HT concentrations than cows, and calves born to TRT cows had increased 5-HT concentrations compared with the CON. Precalving milking could affect 5-HT synthesis within the mammary gland and therefore affect maternal 5-HT and calcium concentrations. Further research is needed in ruminants to assess the extent of 5-HT placental transfer, its role on pre- and postnatal development of the calf, the importance of its presence in colostrum, and potential long-term effects on calf health

Milk production during the colostral period is not related to the later lactational performance in dairy cows

In dairy cows, milk yield increases rapidly after parturition until a peak at around wk 6 of lactation. However, the description of the shape of the lactation curve is commonly based on weekly average milk yields. For a more detailed analysis of the milk production curve from the very beginning of lactation including the colostral period and the effect of colostrum yield on further lactational performance, the first 10 milkings after parturition, daily milk yields from d 1 to 28 of lactation, and the cumulative milk production on d 100 to 305 of lactation were investigated in 17 primiparous and 39 multiparous cows milked twice daily. Milk yield at the first milking after parturition (colostrum) ranged from 1.3 to 20.7kg (Δ=19.4kg) in multiparous and from 1.8 to 10.9kg in primiparous animals (Δ=9.1kg). At the tenth milking, milk production ranged from 9.2 to 21.5kg (Δ=12.3kg) in multiparous and from 7.0 to 15.2kg (Δ=8.2kg) in primiparous animals. Immediately after parturition, daily milk production increased rapidly, but after approximately 1wk in lactation, the slope of the daily milk production curve flattened and continued more linear. A nonlinear regression equation was used to determine this timely change, which occurred earlier in primiparous (d 6.9±0.3) than in multiparous cows (d 8.2±0.2). The correlation between the amount of first colostrum and milk production during further lactation decreased already from 0.47 on d 5 to 0.32 on d 14. In multiparous cows, the correlation between total milk production of the previous 305d standard lactation and the amount of first colostrum was not significant (correlation=0.29), whereas the correlation with the daily production increased from 0.45 on d 5 to 0.69 on d 14. However, in primiparous animals, correlations between first-colostrum yield and daily milk yields up to d 28 of lactation were not significant, possibly due to the smaller sample size compared with multiparous animals. First-colostrum yield and cumulative milk production of 100, 200, and 305 lactation days were not significantly correlated in multiparous and primiparous cows. In conclusion, the milk production during the first few milkings is widely independent from the overall production level of a cow. Potentially, genetic selection toward lower milk yield during the very first days after parturition at a simultaneously high lactational performance may be a tool to ensure sufficient colostrum quality and to reduce the metabolic load around parturition.

Cholesterol metabolism, transport, and hepatic regulation in dairy cows during transition and early lactation

The transition from the nonlactating to the lactating state represents a critical period for dairy cow lipid metabolism because body reserves have to be mobilized to meet the increasing energy requirements for the initiation of milk production. The purpose of this study was to provide a comprehensive overview on cholesterol homeostasis in transition dairy cows by assessing in parallel plasma, milk, and hepatic tissue for key factors of cholesterol metabolism, transport, and regulation. Blood samples and liver biopsies were taken from 50 multiparous Holstein dairy cows in wk 3 antepartum (a.p.), wk 1 postpartum (p.p.), wk 4 p.p., and wk 14 p.p. Milk sampling was performed in wk 1, 4, and 14 p.p. Blood and milk lipid concentrations [triglycerides (TG), cholesterol, and lipoproteins], enzyme activities (phospholipid transfer protein and lecithin:cholesterol acyltransferase) were analyzed using enzymatic assays. Hepatic gene expression patterns of 3-hydroxy-3-methylglutaryl-coenzyme A (HMGC) synthase 1 (HMGCS1) and HMGC reductase (HMGCR), sterol regulatory element-binding factor (SREBF)-1 and -2, microsomal triglyceride transfer protein (MTTP), ATP-binding cassette transporter (ABC) A1 and ABCG1, liver X receptor (LXR) α and peroxisome proliferator activated receptor (PPAR) α and γ were measured using quantitative RT-PCR. Plasma TG, cholesterol, and lipoprotein concentrations decreased from wk 3 a.p. to a minimum in wk 1 p.p., and then gradually increased until wk 14 p.p. Compared with wk 4 p.p., phospholipid transfer protein activity was increased in wk 1 p.p., whereas lecithin:cholesterol acyltransferase activity was lowest at this period. Total cholesterol concentration and mass, and cholesterol concentration in the milk fat fraction decreased from wk 1 p.p. to wk 4 p.p. Both total and milk fat cholesterol concentration were decreased in wk 4 p.p. compared with wk 1 and 14 p.p. The mRNA abundance of genes involved in cholesterol synthesis (SREBF-2, HMGCS1, and HMGCR) markedly increased from wk 3 a.p. to wk 1 p.p., whereas SREBF-1 was downregulated. The expression of ABCA1 increased from wk 3 a.p. to wk 1 p.p., whereas ABCG1 was increased in wk 14 p.p. compared with other time points. In conclusion, hepatic expression of genes involved in the biosynthesis of cholesterol as well as the ABCA1 transporter were upregulated at the onset of lactation, whereas plasma concentrations of total cholesterol, phospholipids, lipoprotein-cholesterol, and TG were at a minimum. Thus, at the gene expression level, the liver seems to react to the increased demand for cholesterol after parturition. Whether the low plasma cholesterol and TG levels are due to impaired hepatic export mechanisms or reflect an enhanced transfer of these compounds into the milk to provide essential nutrients for the newborn remains to be elucidated.

Increased periodontal inflammation in women with preterm premature rupture of membranes

OBJECTIVES To evaluate possible differences in periodontal inflammatory, microbiological and clinical parameters between women with preterm premature rupture of membranes (PPROM) and controls with uncomplicated pregnancies. MATERIALS AND METHODS Fifty-six women (32 test (PPROM) and 24 controls (uncomplicated pregnancies)) were examined at three time-points (T1: gestational weeks 20-35, T2: within 48 h after parturition, T3: 4-6 weeks after parturition). The examinations included assessment of the Periodontal Screening Index, collection of gingival crevicular fluid (GCF) and subgingival as well as vaginal bacterial sampling. RESULTS Periodontal inflammation was found to be higher in the test compared with the control group (p < 0.05) and decreased over time in both groups (p < 0.05). Microbiological outcomes showed no intergroup differences (p > 0.05) in prevalence of bacteria, but a decrease in subgingival periodontopathogens from T1 to T2 in the test group (p < 0.05) was observed. Interleukin (IL)-1β levels in GCF at T2 were not different between groups (p > 0.05). In women with PPROM, GCF levels of IL-8 (p < 0.05) and C-reactive protein (p < 0.05) were lower and IL-10 levels higher (p < 0.05) compared with controls. CONCLUSIONS Periodontal inflammation is elevated during pregnancy and seems to be more pronounced in women with PPROM. CLINICAL RELEVANCE The findings of the present study revealed an association between periodontal inflammation and PPROM, thus emphasizing the importance of optimizing self-performed oral hygiene in pregnant women.

Uterine torsion in Brown Swiss cattle: retrospective analysis from an alpine practice in Switzerland

The incidence of uterine torsion in cattle is 0.5–1 per cent of all calvings and up to 30 per cent of all dystocia cases (Berchtold and Rüsch 1993). The unstable suspension of the bovine uterus is a predisposition cited by different authors (Pearson 1971, Schulz and others 1975, Berchtold and Rüsch 1993). Age of the cow, season and weight and sex of the calf have been inconsistently reported to be associated with uterine torsion (Distl 1991, Frazer and others 1996, Tamm 1997). Small amount of fetal fluids and a large abdomen may contribute to uterine torsion (Berchtold and Rüsch 1993). Furthermore, some authors describe a predisposition in the Brown Swiss breed (Distl 1991, Schmid 1993, Frazer and others 1996) and in cows kept in alpine regions (Schmid 1993). Uterine torsion is predominantly seen under parturition, and the degree of torsion is most often between 180° and 360°. The direction is counter-clockwise in 60–90 per cent of the cases (Pearson 1971, Berchtold and Rüsch 1993, Erteld and others 2012). Vaginal delivery is possible after manual detorsion or after rolling of the cow, whereas caesarean section has to be performed after unsuccessful detorsion or if the cervix is not dilating adequately following successful correction of the torsion (Berchtold and Rüsch 1993, Frazer and others 1996). Out of all veterinary-assisted dystocia cases, 20 per cent (Aubry and others 2008) to 30 per cent (Berchtold and Rüsch 1993) are due to uterine torsion. Many publications describe fertility variables after dystocia, but only Schönfelder and coworkers described that 40 per cent of the cows got pregnant after uterine torsion followed by caesarean section (Schönfelder and Sobiraj 2005).

Effect of starch substitution with crude glycerol on growing rabbit and lactating doe performance

The aim of this work was to study the effect of dietary inclusion of 2.5 or 5.0% of glycerol in substitution for starch on performance of lactating does and fattening rabbits. Over four consecutive reproductive cycles, a total of 81 New Zealand ´ Californian rabbit does and 813 young rabbits weaned at 25 (fattening trial 1) or 35 (fattening trial 2) days of age were allocated at random to the experimental treatments. Inclusion of glycerol in the diet up to 5% did not influence total feed consumption of does and suckling rabbits, body weight and bioelectrical impedance of does at parturition or at day 21 of lactation and litter weight at weaning, or reproductive efficiency. Substitution of starch with glycerol did not affect feed intake, weight gain or mortality during fattening. The results of the current study indicate that crude glycerol from the biofuel industry can be used at levels up to 5% in rabbit diets without any detrimental or beneficial effect on performance

Optimizing rabbit production under heat stress: cage density and cage size during fattening, and breeding system and water quality on rabbit does

The aim of this work was to evaluate different management strategies to optimize rabbit production under chronic heat stress. To achieve it, three trials were conducted. In the first trial, to find the optimal cage density in tropical very dry forest condition, were measured growth performance, mortality rate, injured animals and carcass performance over an initial population of 300 cross-breed rabbits of New Zealand, California, Butterfly, Dutch and Satin, weaned at 30 days (535 ± 8 g, standard error). Treatments evaluated were: 6, 12, 18 and 24 rabbits/m2 (3, 6, 9 and 12 rabbits/cage, respectively, each cage of 0.5 m2). The maximal temperature-humidity index indicated a severe heat stress from weaning to 2.2 kg body weight (experimental time). At the end of experimental period 10, 20, 30 and 30 rabbits from the treatments of 6, 12, 18 and 24 rabbits/m2, respectively, were slaughtered and carcass performance recorded. Average daily gain and feed intake decreased by 0.31 ± 0.070 and 1.20 ± 0.25 g, respectively, per each unit that the density increased at the beginning of the experiment (P = 0.001). It increased the length of the fattening period by 0.91 ± 0.16 d (P = 0.001) per each unit of increment of density. However, rabbit production (kg/m2) increased linear and quadratically with the density (P < 0.008). Animals housed at the highest density compared to the lower one tended to show a higher incidence of ringworm (68.9 vs 39.4%; P = 0.075), injured animals (16.8 vs 3.03%; P = 0.12) and mortality (20.5 vs 9.63%; P = 0.043). The proportion of scapular fat (P = 0.042) increased linearly with increasing levels of density. Increasing density reduced linearly dorsal length (P = 0.001), and reduced linear and quadratically drip loss percentage (P = 0.097 and 0.018, respectively). In the second trial, 46 nulliparous rabbit does (23 clipped and 23 unclipped) with a BW of 3.67 ± 0.05 kg (s.e.) were used to evaluate heat stress and circadian rhythms comparing unclipped and clipped rabbit does, and to study if a more extensive breeding system increase litters performance at weaning without impairing rabbit doe performance,. Rectal temperature, feed and water 4 intake were recorded for 24 h. Rabbit does were mated 7 d after circadian measurements, and randomly assigned to two breeding systems. Control (C): mated at 14 d after parturition + litter weaned at 35 d of age. Extensive (E): mate at 21 after parturition + litter weaned at 42 d of age. The first three cycles were evaluated concerning to rabbit doe and litter performance. Two hundred twenty eight weaned rabbits, were divided into two cage sizes: 0.5 and 0.25 m2 with same density (16 rabbit/m2) and growing performance was recorded. Farm and rectal temperatures were minimal and feed and water intake maximal during the night (P < 0.001). Unclipped rabbit does showed higher rectal temperature (P = 0.045) and lower feed intake respect to clipped does (P = 0.019) which suggest a lower heat stress in the latter. Kits weaned per litter was reduced by 33% (P=0.038) in C group. This reduction was more important in the 2nd and 3rd cycles compared to the first (P ≤ 0.054). Rabbit doe feed efficiency tended to decrease in E respect C group (P = 0.093), whereas it was impaired from the first to the third cycle by 48% (P = 0.014). Growing rabbits from the E group were heavier at weaning (by 38%. P < 0.001), showed a higher feed intake (+7.4%) and lower feed efficiency (-8.4%) throughout the fattening period (P ≤ 0.056) respect to C group. Cage size had minor influence in growing performance. In the third trial, forty five non pregnant and non lactating rabbit does (21 nulliparous and 24 multiparous) were assigned randomly to farm water and to potable water to study if a water quality improvement can affect positively rabbit doe response to heat stress during pregnancy and lactation. A transponder was implanted in each animal to record subcutaneous temperature at 07:30 and 14:30 h. Experimental period extended from pregnancy (with no lactation) to the next lactation (until day 28). Body temperature and milk production were recorded daily, and body condition, feed and water intake weekly. Water quality did not affect any trait (P ≥ 0.15). Pregnant rabbit does were classified as does that weaned (W: 47%), not weaned (NW: 44%) or those pregnant that did not deliver (NB: 9%). Body temperature and feed intake decreased during pregnancy (P ≤ 0.031), but water intake remained constant. In this period body temperature decreased with metabolic weight (P ≤ 0.009). In W and NW does, 5 from mating to birth energy and protein balance impaired (P≤0.011). Body temperature of W does tended to be the lowest (P ≤ 0.090). Pregnancy length and total number of kits born tended to be longer and higher in NW than in W does (P = 0.10 and 0.053, respectively). Kit mortality at birth and from birth to 14 d of lactation was high, being worse for NW than for W does (97 vs. 40%; P<0.001). Body temperature during lactation was maximal at day 12, and milk production increased it (P ≤ 0.025). . In conclusion, in our heat stress conditions densities higher than 18 rabbits/m2 (34 kg/m2) at the end of fattening, are not recommended despite cage size, gestation and lactation productivity impaired not only when lactation is extended and along successive reproductive cycles but also due to a reduced embryo/kit survival and finally water quality improvement did not attenuate negative effect of heat stress. RESUMEN El propósito de éste trabajo fue evaluar diferentes estrategias de manejo para optimizar la producción de conejos bajo estrés térmico. Para lo cual se desarrollaron tres experimentos. En el primer experimento, para encontrar el número óptimo de gazapos por m2 de jaula durante el cebo en condiciones de bosque muy seco tropical, se estudiaron los rendimientos durante el cebo, mortalidad, animales lesionados y rendimiento de la canal sobre una población inicial de 300 conejos mestizos de Nueva Zelanda, California, Mariposa, Holandés y Satin, destetados a los 30 días de edad (535 ± 8g, error estándar). Los tratamientos evaluados fueron: 6, 12, 18 y 24 conejos/m2 (3, 6, 9 y 12 conejos/jaula, respectivamente, en jaulas de 0.5 m2). Durante el período experimental (destete a 2.2 kg de peso vivo), se observaron valores de THI correspondientes con un estrés térmico severo (THI max. De 31 a 35). Al final del período experimental, 10, 20, 30, y 30 conejos de los tratamientos con densidades de 6, 12, 18 y 24 conejos/m2, respectivamente, fueron sacrificados y su canal fue valorada. El promedio de la ganancia diaria y el consumo de alimento disminuyeron en 0.31 ± 0.070 y 1.20 ± 0.25 g, respectivamente, por cada unidad de incremento en la densidad al inicio del experimento (P=0.001). Esto alargó el período de engorde en 0.91 ± 0.16 d (P=0.001) por cada unidad de incremento de la densidad. Sin embargo, la producción de conejos (kg/m2) aumentó lineal y cuadráticamente con la densidad (P<0.008). Los animales alojados en las mayores densidades en comparación con el resto tendieron a mostrar una mayore incidencia de tiña (68.9 vs 39.4%; P=0.075), de cantidad de animales heridos (16.8 vs 3.03%; P=0.12), así como de mortalidad (20.5 vs 9.63%; P=0.043). El aumento en la densidad aumentó linealmente la proporción de grasa escapular (P=0.042) y redujo linealmente la longitud dorsal (P=0.001), y lineal y cuadráticamente el porcentaje de pérdida por goteo (P=0.018). En el segundo experimento, 46 conejas nulliparas (23 rasuradas y 23 no rasuradas) con un peso vivo de 3.67 ± 0.05 kg (e.e.) fueron usadas para evaluar el estrés 8 térmico y los ritmos circadianos comparando conejas rasuradas o no, y estudiar si un sistema de crianza más extensivo mejora el desempeño de la camada al destete sin perjudicar la productividad de la coneja. Durante 24 h se midió la temperatura rectal, consumo de alimento y de agua. Las conejas fueron montadas 7 días después, y distribuidas en dos sistemas de crianza. El control (C): monta a 14 días posparto y destete a 35 d de edad. El extensivo (E): monta a 21 días posparto y destete a 42 d de edad. Se controló la productividad de la coneja y la camada durante los tres primeros ciclos. Doscientos veintiocho gazapos fueron distribuidos en dos tamaños de jaulas (0.5 y 0.25 m2) con la misma densidad (16 conejos/m2) y se controlaron sus rendimientos productivos. Durante la noche se observaron los valores mínimos para la temperatura ambiental y rectal, y los máximos para consumo de alimento y agua (P< 0.001). Las conejas no rasuradas mostraron mayor temperatura rectal (P=0.045) y menores valores de consumo de alimento con respecto a las conejas rasuradas (P=0.019), lo que sugiere un menor estrés térmico en las últimas. El número de gazapos destetados por camada se redujo en 33% (P=0.038) en el grupo C. Este comportamiento se acentuó en el 2do y 3er ciclo en comparación con el primero (P≤0.054). La eficiencia alimenticia de las conejas tendió a disminuir en el grupo E con respecto al grupo C (P=0.093), dicha tendencia se acentúa del primer al tercer ciclo en un 48% (P=0.014). Los gazapos en fase de crecimiento provenientes del grupo E fueron más pesados al momento del destete (en 38% P<0.001), mostrando un mayor consumo de alimento (+7.4%) y menor eficiencia alimenticia (-8.4%) a lo largo del engorde (P≤0.056) con respecto al grupo C. El tamaño de la jaula tuvo una mínima influencia en el comportamiento durante el crecimiento de éstos gazapos. En el tercer experimento, cuarenta y cinco conejas no gestantes ni lactantes (21 nulíparas y 24 multíparas) se les asignó al azar agua dos tipos de agua: común de la granja y agua potable, con el fin de estudiar si una mejora en la calidad del agua puede afectar positivamente la respuesta de la coneja al estrés térmico durante la gestación y la lactancia. Se les implantó un transponder para registrar la temperatura subcutánea a las 7:30 y a las 14:30 h. El período experimental se extendió desde la gestación (sin 9 lactancia) hasta la lactanción consecutiva (hasta los 28 días). La temperatura corporal y la producción de leche se controlaron diariamente, y la condición corporal, consumo de agua y alimento, semanalmente. La calidad del agua no afectó a ninguna variable (P≥0.15). Las conejas preñadas fueron clasificadas como conejas que destetaron (W: 47%), que no destetaron (NW:44%) o aquellas que no parieron (NB: 9%). La temperatura corporal y consumo de alimento disminuyeron durante la gestación (P≤0.031), mientras que el consumo de agua se mantuvo constante. La temperatura corporal descendió con el peso metabólico durante la gestación (P≤0.009). El balance de energía y proteína disminuyó desde la monta al parto para las conejas W y NW (P≤0.011). Durante la gestación la temperatura corporal tendió a ser menor en las conejas W (P≤0.090). La longitud de la gestación y el número total de gazapos nacidos tendieron a ser mayores en conejas NW que en conejas W (P=0.10 y 0.053, respectivamente). La mortalidad de los gazapos al parto y del parto a los 14 días de lactancia fue alta, siendo peor para las conejas NW que para las W (97 vs 40%; P<0.001). Durante la lactancia la temperatura corporal alcanzó su valor máximo para el día 12, y la producción de leche indujo un incremento en la misma (P≤0.025). En conclusión, en nuestras condiciones de estrés térmico y sin importar el tamaño de la jaula, no se recomiendan densidades mayores a 18 conejos/m2 (34 kg/m2) al final del engorde. La productividad de la gestación y la lactancia disminuyen cuando la lactancia es mayor y se suceden varios ciclos reproductivos seguidos. Esto se debe al efecto negativo del estrés térmico sobre la vitalidad y supervivencia del embrión/gazapo. La mejora de la calidad del agua atenuó el efecto negativo del estrés térmico. Las conejas más productoras parece que son aquéllas que consiguen manejar mejor el estrés térmico.

Biostimulation methods associated with early weaning and reproductive rhythms in primiparous rabbit does

El objetivo general de esta Tesis Doctoral ha sido tratar de mejorar los parámetros reproductivos de las conejas primíparas lactantes, empleando dos métodos de manejo (destete temprano y extensificación del ritmo reproductivo), que están directamente relacionados con su balance energético. Para ello, se diseñaron 2 experimentos en este tipo de hembras. En el primero, se estudió el efecto del destete a 25 días post-parto (dpp) sobre la actividad ovárica y el metabolismo energético de las conejas una semana más tarde (32 dpp). Un total de 34 primíparas lactantes con 8 gazapos fueron distribuidas en tres grupos: 10 conejas se sacrificaron a los 25 dpp (grupo L25), 13 fueron destetadas a los 25 dpp y sacrificadas a los 32 dpp (grupo NL32), y 11 conejas no se destetaron y fueron sacrificadas a los 32 dpp (grupo L32). No se observaron diferencias significativas entre grupos en el peso corporal, el peso del ovario, ni en las concentraciones séricas de ácidos grasos no esterificados y de proteínas totales. A pesar de que el grupo NL32 presentó un bajo consumo de alimento (122 ± 23,5 g / día, p <0,001), su contenido corporal estimado de lípidos (16,9 ± 1,09%, P <0,008), proteínas (19,7 ± 0,07%, P <0,0001), y energía (1147 ± 42,7 MJ / kg, p <0,006) fueron más elevados y las concentraciones séricas de glucosa (158 ± 24,5 mg/dl, p <0,04) más bajas que en los grupos L25 (11,9 ± 1,3%, 18,5 ± 0,08%, 942 ± 51,3 MJ/kg y 212 ± 27,9 mg/dl) y L32 (13,4 ± 1,03%, 18,5 ± 0,1%, 993 ± 40,4 MJ/kg y 259 ± 29,5 mg/dl), respectivamente. En el grupo L25 se observó un menor número medio de folículos ≥ 1 mm en la superficie ovárica en comparación con los grupos NL32 y L32 (12,7 ± 1,5 vs. 18,0 ± 1,45 y 17,6 ± 1,67, p <0,05). La población folicular ovárica en las secciones histológicas y la inmunolocalización de los receptores de prolactina fueron similares en todos los grupos. En el grupo L25, tanto la maduración nuclear de oocitos, medida en términos de tasas alcanzadas de Metafase II (67,0 vs. 79,7 y 78,3%, P <0.05) y la maduración citoplasmática, medida por el porcentaje de gránulos corticales (GC) total o parcialmente migrados en los oocitos, fueron significativamente menores que en los grupos NL32 y L32 (16,0 vs 38,3 y 60,0%, P <0.05). En conclusión, a pesar de que el destete precoz a 25 dpp pareció mejorar las reservas de energía de las conejas primíparas, este hecho no se reflejó claramente a nivel ovárico a los 32 dpp y fue similar independientemente del destete, por lo que éste último podría llevarse a cabo más tarde. En el segundo experimento, se compararon dos ritmos reproductivos. Se utilizaron un total de 48 conejas primíparas lactantes con 8 gazapos que se asignaron al azar en dos grupos experimentales: a) lactantes sacrificadas a comienzos del post-parto (11 dpp) de acuerdo a un ritmo semi-intensivo (n = 24), y b) lactantes sacrificadas al final del período post-parto (25 dpp) de acuerdo con un ritmo más extensivo (n = 24). En ellas, se estudió el peso vivo, la composición corporal estimada, parámetros metabólicos y endocrinos (estradiol y progesterona) y características ováricas como la población folicular y la tasa de atresia, así como la maduración nuclear y citoplásmica de los oocitos. En este estudio, el peso vivo, el contenido de energía corporal, los depósitos grasos y los ácidos grasos no esterificados disminuyeron a lo largo del post-parto con respecto al momento del parto (P <0,05). Las concentraciones séricas de proteínas y glucosa aumentaron en el mismo periodo post-parto (P <0,05). Se observaron similares niveles de estradiol y progesterona en ambos ritmos, así como una población folicular, tasas de maduración nuclear (tasa de oocitos en metafase II) y citoplasmática (porcentaje de oocitos con gránulos corticales migrados), similares en ambos momentos del post-parto. Sin embargo, el número de folículos preovulatorios en la superficie ovárica fue menor (P <0,05) y la tasa de atresia tendió a ser mayor con un porcentaje también menor de folículos sanos (P <0,1) en los ovarios de las hembras sometidas al ritmo extensivo. En conclusión, al final del post-parto (25 días), las conejas primíparas sin destetar muestran un deterioro de sus reservas corporales, de sus parámetros metabólicos séricos y de la calidad de sus oocitos; incluso se ha observado una ligera influencia negativa en el desarrollo de sus folículos ováricos. Por esta razón, se considera que en las conejas primíparas lactantes el manejo reproductivo extensivo (25 dpp) no presenta ninguna ventaja en comparación con el semi-intensivo (11 dpp). A la vista de los resultados de estos dos experimentos, podemos decir que ni el destete temprano, ni la extensificación del ritmo reproductivo han conseguido una mejora en los parámetros reproductivos de una hembra primípara. Por ello, son necesarios más estudios sobre el estado metabólico de la coneja primípara lactante para conseguir métodos o estrategias que lo mejoren y tengan consecuencias directas sobre la actividad reproductiva y sobre su éxito productivo. The general aim of this Thesis was to study two management methods (early weaning and extensive reproductive rhythm) linked to the energy balance of the primiparous rabbit does to improve their reproductive performance. In this sense, 2 experiments were conducted using this kind of females. In the first experiment, the effect of weaning at 25 days post-partum (dpp) on ovarian activity and energetic metabolism one week later (32 dpp) was studied. A total of 34 primiparous lactating rabbit does were used and distributed among three groups: 10 does euthanized at 25 dpp (group L25), 13 does weaned at 25 dpp and euthanized at 32 dpp (group NL32), and 11 non weaned does euthanized at 32 dpp (group L32). No significant differences were observed in live body weight, ovary weight, serum non esterified fatty acids (NEFA) and total protein concentration among groups. Although NL32 does had a low feed intake (122±23.5 g/Day; P < 0.001), their estimated lipids (16.9±1.09%, P < 0.008), protein (19.7±0.07%, P < 0.0001), and energy (1147±42.7 MJ/kg, P < 0.006) body contents were higher and their serum glucose concentrations (158±24.5 mg/dl, P < 0.04) were lower compared to L25 does (11.9±1.3%, 18.5±0.08%, 942±51.3 MJ/kg and 212±27.9 mg/dl) and L32 does (13.4±1.03%, 18.5±0.1%, 993±40.4 MJ/kg and 259±29.5 mg/dl, respectively). A lower number of follicles ≥1mm was observed compared to NL32 and L32 groups (12.7±1.5 vs. 18.0±1.45 and 17.6 ±1.67; P < 0.05) in the ovarian surface of L25 does. Follicular population in the histological ovarian sections and immunolocalization of prolactin receptor were similar in all groups. In group L25, both nuclear maturation of oocytes in terms of Metaphase II rate (67.0 vs. 79.7 and 78.3%; P < 0.05) and cytoplasmic maturation measured by percentage of cortical granules (CG), totally or partially migrated in oocytes were significantly lower than in groups NL32 and L32 (16.0 vs. 38.3 and 60.0%; P < 0.05). Consequently, a higher rate of oocytes with non-migrated CGs was found in group L25 than in groups NL32 and L32 (76.0 vs. 46.8 and 33.3%; P < 0.05). In conclusion, even though early weaning at 25 dpp seemed to improve body energy stored in primiparous does, this fact was not well reflected on the ovarian status at 32 dpp, which was similar regardless of weaning time. In the second experiment, two reproductive rhythms were compared. A total of 48 primiparous Californian x New Zealand White rabbit does suckling 8 kits were randomly allocated in two experimental groups: a) lactating does euthanized at early post-partum period (11 dpp) according to a semi-intensive rhythm (n = 24), and b) lactating does euthanized on later post-partum period (25 dpp) according to a more extensive rhythm (n = 24). Live weight, estimated body composition, serum metabolic and endocrine parameters (oestradiol and progesterone concentrations) and ovarian features like follicle population and atresia rate, and oocyte maturation were studied. Live weight, body energy content, lipid depots and serum non esterified fatty acids (NEFA) concentrations diminished from parturition time to post-partum period (P < 0.05). In addition, serum protein and glucose concentrations increased along postpartum time (P < 0.05). Similar oestradiol and progesterone levels were shown in rhythms as well as similar follicle population and nuclear and cytoplasmic maturation rates measured as metaphase II and cortical granule migration, respectively in both postpartum times. However, number of preovulatory follicles on the ovarian surface was lower (P < 0.05) and atresia rate tended to be higher with also lower percentage of healthy follicles (P < 0.1) in ovaries of females of extensive group. In conclusion, primiparous non-weaned rabbits does at late post-partum time (25 days), Did no show any improvement regarding body reserves, serum metabolic parameters and oocyte quality; even a slight negative influence has been observed in the development of their ovarian follicles. Thus this reproductive management does not present any advantage compared to earlier post-partum (11 days) reproductive rhythm. In summary, according to the obtained results from these two experiments, we can say that the application of early weaning and the extensive rhythms did not achieve an improvement in the reproductive performance of primiparous does. Thus, it is necessary to conduct more studies about the metabolic status of the primiparous lactating doe to achieve strategies in order to improve it and consequently, to improve the reproductive activity and their productive success.

Reproductive long-term effects, endocrine response and fatty acid profile of rabbit does fed diets supplemented with n-3 fatty acids

The effect of a diet enriched with polyunsaturated n -3 fatty acids (PUFA) on endocrine, reproductive, and productive responses of rabbit females and the litters has been studied. Nulliparous does ( n = 125) were fed ad libitum from rearing to second weaning two diets supplemented with different fat sources: 7.5 g/kg lard for the control diet (group C; n = 63) or 15 g/kg of a commercial supplement containing a 50% ether extract and 35% of total fatty acids (FAs) as PUFA n -3 (Group P; n = 62). Dietary treatments did not affect apparent digestibility coefficients of nutrients, or reproductive variables of does including milk pro- duction, mortality and average daily gain of kits over two lactations. However, on Day 5 and 7 post-induction of ovulation, progesterone of Group P tended to increase to a greater extent than in does of Group C. Total PUFAs, n -6 and n -3 and eicosapentanoic (EPA) contents were greater in adipose tissues of does in Group P than in Group C. Docosapentaenoic acid (DPA), EPA, and docosahexaenoic acid (DHA) concentrations were greater in peri-ovarian than in scapular fat with abdominal fat being intermediate in concentration. In PUFA sup- plemented does, kit mortality at the second parturition tended to be less than in control does. Also, kits born to does of the PUFA-supplemented group weighed more and were of greater length than from does of control group. In conclusion, effectiveness of dietary intervention on reproductive and performance response is greater in the second parity, which suggests an accumulative long-term beneficial effect of n -3 FA supplementation in reproductive rabbit does

Effect of late weaning and use of alternative cages on performance of does, suckling and fattening rabbits under extensive reproductive management

The effects of the combined use of long lactation periods (46 days) with alternative cages on the reproductive and growth performance of 104 rabbit does and their litters during five consecutive reproductive cycles were studied. Half of does were housed in conventional polyvalent cages (39 cm×100 cm×30 cm) and the other half in alternative polyvalent cages (39 cm×100 cm×60 cm), with a raised platform. Half of the rabbit does in each type of cage were weaned at 32 and the other half at 46 days after parturition. Longer lactation negatively affected the body weight (P<0.001), fat and energy content (P<0.05) of rabbit does at the end of the lactation period, but this effect decreased with the number of parturitions. Fertility, prolificacy and doe mortality were not affected by lactation length. Late weaning led to higher litter size (by 8.9%) and litter weight (by 11.3%) at the end of growing period (P<0.001) and lower feed conversion ratio per cage during the experimental period (13.5%) than weaning at 32 day (P<0.001). These results were paralleled by lower mortality (12.6 vs. 17.6%; P<0.01) of young rabbits weaned later during the overall experimental period. Differences in performance as a result of different weaning ages were only observed during cycles with worst health status (third and fifth cycles) in which late weaning decreased mortality. Type of cage did not affect doe body weight and body condition, mortality, fertility, prolificacy and litter size during the five reproductive cycles. Nevertheless, at day 21 litter weight and feed conversion ratio between 3 and 21 day were 4.2% higher (P<0.01) and 5.0% lower (P<0.05), respectively, in animals housed in alternative rather than in conventional cages. Alternative cages also led to heavier litters at 59 days (P<0.01). It was concluded that the combined use of longer lactations and cages with higher available surface with a raised platform could be alternatives to improve animal welfare in farmed rabbit.

Effect of late weaning and use of alternative cages on performance of does, suckling and fattening rabbits under extensive reproductive management

The effects of the combined use of long lactation periods (46 days) with alternative cages on the reproductive and growth performance of 104 rabbit does and their litters during five consecutive reproductive cycles were studied. Half of does were housed in conven- tional polyvalent cages (39 cm x 100 cm x 30 cm) and the other half in alternative polyvalent cages (39 cm x 100 cm x 60 cm), with a raised platform. Half of the rabbit does in each type of cage were weaned at 32 and the other half at 46 days after parturition. Longer lactation negatively affected the body weight ( P o 0.001), fat and energy content ( P o 0.05) of rabbit does at the end of the lactation period, but this effect decreased with the number of parturitions. Fertility, prolificacy and doe mortality were not affected by lactation length. Late weaning led to higher litter size (by 8.9%) and litter weight (by 11.3%) at the end of growing period ( P o 0.001) and lower feed conversion ratio per cage during the experimental period (13.5%) than weaning at 32 day ( P o 0.001). These results were paralleled by lower mortality (12.6 vs. 17.6%; P o 0.01) of young rabbits weaned later during the overall experimental period. Differences in performance as a result of different weaning ages were only observed during cycles with worst health status (third and fifth cycles) in which late weaning decreased mortality. Type of cage did not affect doe body weight and body condition, mortality, fertility, prolificacy and litter size during the five reproductive cycles. Nevertheless, at day 21 litter weight and feed conversion ratio between 3 and 21 day were 4.2% higher ( P o 0.01) and 5.0% lower ( P o 0.05), respectively, in animals housed in alternative rather than in conventional cages. Alternative cages also led to heavier litters at 59 days ( P o 0.01). It was concluded that the combined use of longer lactations and cages with higher available surface with a raised platform could be alternatives to improve animal welfare in farmed rabbit.