Effects of age at first calving, gestation length and dry period on milk yield in a Gyr herd

Relationships of several reproductve traits and milk yield were studied in 716 Gyr cows at Sant'Ana da Serra farm, Mococa, State of São Paulo, a humid tropical climate region. Mean age at first calving was 49.8 +/- 0.4 months, with a coeficient of cariation (C. V.) of 20.8%. Only year of parturition significantly affected age at first calving (P < 0.01). Heritability, estimated from paternal half-sib correlations, was 0.91 +/- 0.20, a value considered unrealistically high. Overall mean gestation length was 287.7 +/- 0.5 days (C. V. = 3.3%) for 419 observations, with month and year of parturition having significant effects. Heritability estimate was 0.30 +/- 0.14. Overall mean dry period for 1.276 observations was 238 +/- 3 days (C. V. = 48%); repeatability estimate was 0.19 +/- 0.06. Estimated annual genetic trend for dry period was -0.6 days, phenotypic trend was 11.5 days, and environmental trend, 12.1 days. Month and year of parturition and cow age had no significant effect on dry period. Highest milk yield was obtained at fourth lactation. The gross correlation between milk yield and gestation period was 0.11, and between previous dry period and subsequent milk yield, 0.16. Normal gestations of 285 to 290 days were associated with higher milk yields. Milk yield increased as dry period advanced from 30 to 390 days, and declined as dry period continued beyond 390 days. Delays in first mating and a more extensive dry period decreased reproductive efficiency in the herd studied.

Study of fuel cell co-generation systems applied to a dairy industry

This paper presents a methodology for the study of a molten carbonate fuel cell co-generation system. This system is applied to a dairy industry of medium size that typically demands 2100 kW of electricity, 8500 kg/h of saturated steam (P = 1.08 MPa) and 2725 kW of cold water production. Depending on the associated recuperation equipment, the co-generation system permits the recovery of waste heat, which can be used for the production of steam, hot and cold water, hot and cold air. In this study, a comparison is made between two configurations of fuel cell co-generation systems (FCCS). The plant performance has been evaluated on the basis of fuel utilisation efficiency and each system component evaluated on the basis of second law efficiency. The energy analysis presented shows a fuel utilisation efficiency of about 87% and exergy analysis shows that the irreversibilities in the combustion chamber of the plant are significant. Further, the payback period estimated for the fuel cell investment between US$ 1000 and US$ 1500/k-W is about 3 and 6 years, respectively. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Factors that cause genotype by environment interaction and use of a multiple-trait herd-cluster model for milk yield of Holstein cattle from Brazil and Colombia

Descriptive herd variables (DVHE) were used to explain genotype by environment interactions (G x E) for milk yield (MY) in Brazilian and Colombian production environments and to develop a herd-cluster model to estimate covariance components and genetic parameters for each herd environment group. Data consisted of 180,522 lactation records of 94,558 Holstein cows from 937 Brazilian and 400 Colombian herds. Herds in both countries were jointly grouped in thirds according to 8 DVHE: production level, phenotypic variability, age at first calving, calving interval, percentage of imported semen, lactation length, and herd size. For each DVHE, REML bivariate animal model analyses were used to estimate genetic correlations for MY between upper and lower thirds of the data. Based on estimates of genetic correlations, weights were assigned to each DVHE to group herds in a cluster analysis using the FASTCLUS procedure in SAS. Three clusters were defined, and genetic and residual variance components were heterogeneous among herd clusters. Estimates of heritability in clusters 1 and 3 were 0.28 and 0.29, respectively, but the estimate was larger (0.39) in Cluster 2. The genetic correlations of MY from different clusters ranged from 0.89 to 0.97. The herd-cluster model based on DVHE properly takes into account G x E by grouping similar environments accordingly and seems to be an alternative to simply considering country borders to distinguish between environments.

Distribution of antibodies against Neospora caninum, BVDV and BHV-1 among cows in brazilian dairy herds with reproductive disorders.

Neospora caninum, bovine viral diarrhea virus (BVDV) and bovine herpes virus 1 (BHV-1) are worldwide spread pathogens associated with reproductive problems in cattle. The present work aimed to observe the infection pattern of these three pathogens in two dairy herds with distinct reproductive managements from Triângulo Mineiro, Minas Gerais State, Brazil. The herds were not vaccinated against either N. caninum, BVDV or BHV-1. Blood samples were collected and analyzed for presence of specific antibodies, and N. caninum IgG avidity was measured in N. caninum positive samples. In herd 1, 34 out of 174 sampled cows (20%) had antibodies to N. caninum and the seropositivity of BVDV and BHV-1 were 62% and 86%, respectively. Of 69 sampled cows in herd 2. 7 (10%) had antibodies to N. caninum, and 49% and 39% were seropositive to BVDV and BHV-1, respectively. The IgG avidity profiles indicated that N. caninum had been present in both herds for some years and that herd 1 had an ongoing horizontal spread of the parasite. The results indicate that the studied reproductive pathogens were present in the herds and partly may have contributed to their reproductive problems.

Analysis of culling probability in dairy buffalo using survival models

In order to contribute to the genetic breeding programs of buffaloes, this study aimed to determine the influence of environmental effects on the stayability (ST) of dairy female Murrah buffalo in the herd. Data from 1016 buffaloes were used. ST was defined as the ability of the female to remain in the herd for 1, 2, 3, 4, 5 or 6 years after the first calving. Environmental effects were studied by survival analysis, adjusted to the fixed effects of farm, year and season of birth, class of first-lactation milk yield and age at first calving. The data were analyzed using the LIFEREG procedure of the SAS program that fits parametric models to failure time data (culling or ST = 0), and estimates parameters by maximum likelihood estimation. Breeding farm, year of birth and first-lactation milk yield significantly influenced (P < 0.0001) the ST to the specific ages (1 to 6 years after the first calving). Buffaloes that were older at first calving presented higher probabilities of being culled 1 year after the first calving, without any effect on culling at older ages. Buffaloes with a higher milk yield at first calving presented a lower culling probability and remained for a longer period of time in the herd. The effects of breeding farm, year of birth and first-lactation milk yield should be included in models used for the analysis of ST in buffaloes. Copyright © The Animal Consortium 2010.

Test-day model for milk yield of dairy buffaloes in colombia

The test-day model is the preferred method for genetic evaluations in dairy cattle. For this study, 28372 test-day records of 1220 lactations from 1997 to 2009 were used. The (co)variance components for milk in test-day were estimated using a Uni and multiple-traits repeated animal model with the Restricted Maximum Likelihood method (REML). The Contemporary Group (herd, year, and season of parity) and the age of parity (linear and quadratic) fixed effects, and the additive genetic, permanent environmental, and residual random effects were included in the model. The heritabilities ranged between 0.06 and 0.45 during lactation. The genetic correlations were greater than 0.93. In conclusion, the test-day model is appropriate for the genetic evaluation of dairy buffaloes in Colombia.

Effects of vaccination against reproductive diseases on reproductive performance of lactating dairy cows submitted to AI

Four experiments evaluated the effects of vaccination against bovine herpesvirus-1 (BoHV-1), bovine viral diarrhea virus (BVDV), and Leptospira spp. on reproductive performance of lactating dairy cows without (experiments 1, 2, and 3) or with previous vaccination against these diseases (experiment 4). Cows were assigned to a fixed-time AI protocol (FTAI; d -11 to 0) in all experiments, as well as AI 12. h upon estrus detection in experiment 3. Pregnancy status was determined with transrectal ultrasonography on d 30 and 71 (d 60 for experiment 3) after AI. Pregnancy loss was considered in cows pregnant on d 30 but non-pregnant on the subsequent evaluation. In experiment 1, 853 cows received (VAC) or not (CON) vaccination against BoHV-1, BVDV, and Leptospira spp. at the beginning of the FTAI (d -11) and 30. d after AI. Pregnancy loss was reduced (P=0.03) in VAC cows compared with CON. In experiment 2, 287 cows received VAC or CON 30. d prior to (d -41) and at the beginning (d -11) of the FTAI. Pregnancy rates on d 30 and 71 were greater (P≤0.03) in VAC cows compared with CON. In experiment 3, 1680 cows with more than 28. d in milk were randomly assigned to receive VAC or CON with doses administered 14. d apart, and inseminated within 15-135. d after the second dose. Pregnancy rates on d 30 and 60 were greater (P≤0.02) in VAC cows compared with CON. In experiment 4, 820 cows received (REVAC) or not (CON) revaccination against BoHV-1, BVDV, and Leptospira spp. at the beginning of the FTAI protocol (d -11). Pregnancy rates and loss were similar (P≥0.54) between treatments. Hence, vaccinating naïve cows against BoHV-1, BVDV, and Leptospira spp. improved reproductive efficiency in dairy production systems, particularly when both doses were administered prior to AI. © 2013 Elsevier B.V.

Analysis of the risk factors related to the immune humoral anti-Anaplasma marginale in dairy cattle

Anaplasma marginale is the most prevalent pathogen of cattle transmitted by ticks in the world. This study aimed to evaluate the risk factors for anaplasmosis in dairy cattle. Fifty dairy cattle from the herd of Empresa de Pesquisa Agropecuaria do Estado do Rio de Janeiro were selected by proportional stratified sampling. The risk factors evaluated were: physiological state, race pattern, number of lactations, milk production, infestation by Rhipicephalus microplus and animal density. Antibody activity against A. marginale was determined using the indirect enzyme-linked immunosorbent assay. The percentual values of seroprevalence for A. marginale were submitted to X2 test, and the level of minimum significance, to keep a factor in the model of logistic regression, was fixated in 5%. It was observed that pregnancy and lactation influenced significantly (p<0.05) in the seropositivity of the animals. Bos indicus animals had 5.21 times more chances of being seropositive than B. taurus animals. Primiparous female had 88% more chances of being seropositive than pluriparous female. Animals with high milk production were 63% more positive than low production animals. When infested by ticks the animals had 39% more chance of being seropositive to A. marginale. Bos indicus animals presented 5.21 times more chance of being seropositive than B. taurus animals. Primiparous females presented 88% more chance of being seropositive than the pluriparous ones. High milk production animals were 63% more positive than the low production ones. When infested by ticks the animals had 39% more chance of being seropositive to A. marginale. High density grazing provided for the animals 3.2 times more chances of being seropositive than low density ones. The herd was classified as erratic to A. marginale, even being placed in a steady enzootic area.

Hormonal treatment of dairy goats affected by hydrometra associated or not with ovarian follicular cyst

Hydrometra is considered a very important pathological condition, because it represents one of the main causes of temporary infertility in dairy goats. The objective was (i) to evaluate a protocol for the treatment of hydrometra associated (n=2) or not (n=17) with follicular ovarian cyst in 19 dairy goats and (ii) to assess its reproductive efficiency after treatment. For this purpose, 10. mg of dinoprost (PGF) divided in two equal doses were administered to all animals intravulvosubmucosally on Days 0 and 10. In addition, 500. IU hCG were administered on Day 7. Ultrasound exams were performed in all females from Days 0 to 3, 7 and 10 to 13 of treatment, in order to evaluate uterus drainage after each treatment. Goats were monitored for estrus after both treatments and mated after the second dose of PGF. Blood samples were collected from 11 goats to determine plasma progesterone concentrations before, during and after treatment. Of the 19 goats treated, 16 lost weight after the first dose, probably due to uterine discharge. Complete drainage of uterine fluid was observed in 11/19 (57.9%) and 17/19 (89.5%) after the first and second doses, respectively. Afterwards, we diagnosed 2 more goats with follicular cysts, for a total of 21.1% (4/19) of animals exhibiting hydrometra and ovarian cyst concomitantly. In one doe the diagnosis was on Day 2 and in the other on Day 11. All does showed progesterone concentrations superior to 1. ng/mL at Day 0, with an average of 10.6 ± 1.4. ng/mL. Out of the 10 goats mated, only two became pregnant after treatment, corresponding to 10.5% of the total (2/19). Although prostaglandin was effective to drain the uterine fluid and led to the onset of estrus, it did not improve the pregnancy rate. The use of hCG in female goats was not effective in luteinizing the cysts. It can be concluded that hydrometra alone or associated with ovarian follicular cyst may adversely affect goat reproductive performance. © 2012 Elsevier B.V.

Nutrients balances and milk fatty acid profile of mid lactation dairy cows supplemented with unsaturated fatty acid

The objective was to evaluate the effect of unsaturated fatty acid sources supplementation on nutrients balances and milk fatty acid profile of mid lactation dairy cows. Twelve Brazilian Holstein cows in the mid lactation (mean of 128 days) and (580 ± 20kg of weight; mean ± SD) with milk yield of 25kg/d were assigned randomly into three 4 × 4 Latin square, fed the following diets: control (C); refined soybean oil; (SO); whole soybean raw (WS) and; calcium salts of unsaturated fatty acids (CSFA). Milk yield was 26.6; 26.4; 24.1 and 25.7 to the diets CO, SO, WS and CSFA respectively. Cows fed the WS treatment produced less milk (1.95kg/d of milk), fat and lactose than did cows fed the SO and CSFA. Cows fed the CSFA treatment showed less blood, urine (g/d) concentrations of N more energetic efficiency and intake of energy than did cows fed the SO treatment. Cows fed the unsaturated fatty acids sources showed more C18:2 cis-9, trans-11 CLA and trans-C18:1 FA concentration in milk than did cows fed the CO treatment. Diets with whole soybeans and soybeans oil provide more efficient digestive processes, and increase milk composition of unsaturated fatty acids.

The application of a surface response methodology in the solar/UV-induced degradation of dairy wastewater using immobilized ZnO as a semiconductor

An Advanced Oxidation Process (AOPs) was carried out in this study with the use of immobilized ZnO and solar/UV as an energy source to degrade dairy wastewater. The semibatch reactor system consisted of metal plate of 800 × 250 mm and a glass tank. The reaction time was of 3 h for 3 L of dairy wastewater. Experiments were performed based on a surface response methodology in order to optimize the photocatalytic process. Degradation was measured in percentage terms by total organic carbon (TOC). The entry variables were ZnO coating thickness and pH, using three levels of each variable. The optimized results showed a TOC degradation of 31.7%. Optimal parameters were metal-plate coating of 100 m of ZnO and pH of 8.0. Since solar/UV is a constant and free energy source in most tropical countries, this process tends to suggest an interesting contribution in dairy wastewater treatment, especially as a pretreatment and the optimal conditions to guarantee a better efficiency of the process. © 2013 Gisella R. Lamas Samanamud et al.

Strategies to improve the efficiency of genomic selection in animal breeding programs

Pós-graduação em Zootecnia - FCAV

Reproductive parameters of dairy goats submitted to estrus synchronization with prostaglandin F2α associated or not to hCG at estrous onset

O objetivo deste estudo foi avaliar a eficiência do uso de duas doses de PGF associadas ou não à administração de hCG no início do estro sobre os parâmetros reprodutivos de cabras leiteiras. Um total de 29 cabras receberam duas doses de 30 µg d-cloprostenol pela via latero-vulvar com 10 dias de intervalo (Dia 1 e Dia 10). As cabras foram alocadas para receberem o hCG (250 IU) ou salina i.m. no momento em que o estro foi detectado. Depois da realização da segunda dose de PGF, o estro foi monitorado e exames ultrassonográficos foram realizados duas vezes ao dia. Todas as fêmeas foram inseminadas 16 h após o inicio do estro. Amostras de sangue foram coletadas diariamente para determinação das concentrações plasmáticas de progesterona. O uso do hCG no momento do início do estro não afetou os parâmetros estudados e, portanto, os dados serão apresentados agrupados. A taxa de manifestação de estro foi similar (P > 0,05) na primeira (75,9% - 22/29) ou na segunda dose de PGF (79,3% - 23/29). O intervalo entre a administração de PGF e o início do estro foi maior (P < 0,05) no Dia 1 (75,8±53,9 h) que no Dia 10 (47,7±10,1 h). Duração do estro também diferiu (P < 0,05) 35,4±15,9 (Dia 1) vs 26,8±15, 0 h (Dia 10). A taxa de ovulação foi 79,3% (23/29) após a segunda dose PGF. Não foi encontrada diferença (P>0,05) entre os grupos experimentais quanto aos parâmetros reprodutivos: intervalo entre a aplicação da segunda dose e a ovulação (86,6±11,4h), intervalo do estro a ocorrência da ovulação (39,9±12,3h), diâmetro do maior folículo (7,2±1,4) e número de ovulações (1,8±0,6). No Dia 1, 52,4% (11/21) apresentavam concentrações de progesterona < 1 ng/mL. No Dia 10, 100% dos animais apresentavam concentrações >1ng/mL. O presente estudo permite concluir que o estro pode ser eficientemente sincronizado em cabras leiteiras com duas doses de PGF intervaladas em 10 dias. Novas pesquisas devem se realizadas para avaliar diferentes doses e momentos de utilização do hCG.

A comparative study of production performance and animal health practices in organic and conventional dairy systems

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)