Effect of somatic cell count and mastitis pathogens on milk composition in Gyr cows

Abstract Background Gyr cows are well adapted to tropical conditions, resistant to some tropical diseases and have satisfactory milk production. However, Gyr dairy herds have a high prevalence of subclinical mastitis, which negatively affects their milk yield and composition. The objectives of this study were (i) to evaluate the effects of seasonality, mammary quarter location (rear x front), mastitis-causing pathogen species, and somatic cell count (SCC) on milk composition in Gyr cows with mammary quarters as the experimental units and (ii) to evaluate the effects of seasonality and somatic cell count (SCC) on milk composition in Gyr cows with cows as the experimental units. A total of 221 lactating Gyr cows from three commercial dairy farms were selected for this study. Individual foremilk quarter samples and composite milk samples were collected once a month over one year from all lactating cows for analysis of SCC, milk composition, and bacteriological culture. Results Subclinical mastitis reduced lactose, nonfat solids and total solids content, but no difference was found in the protein and fat content between infected and uninfected quarters. Seasonality influenced milk composition both in mammary quarters and composite milk samples. Nevertheless, there was no effect of mammary quarter position on milk composition. Mastitis-causing pathogens affected protein, lactose, nonfat solids, and total solids content, but not milk fat content. Somatic cell count levels affected milk composition in both mammary quarters and composite samples of milk. Conclusions Intramammary infections in Gyr cows alter milk composition; however, the degree of change depends on the mastitis-causing pathogen. Somatic cell count is negatively associated with reduced lactose and nonfat solids content in milk. Seasonality significantly affects milk composition, in which the concentration of lactose, fat, protein, nonfat solids and total solids differs between dry and wet seasons in Gyr cows.

Luteal function and follicular growth following follicular aspiration during the peri-luteolysis period in bos indicus and crossbred cattle

Follicular estradiol triggers luteolysis in cattle. Therefore, the control of follicle growth and steroidogenesis is expected to modulate luteal function and might be used as an anti-luteolytic strategy to improve embryo survival. Objectives were to evaluate follicular dynamics, plasma concentrations of estradiol and luteal lifespan in Bos indicus and crossbred cows subjected to sequential follicular aspirations. From D13 to D25 of a synchronized cycle (ovulation = D1), Nelore or crossbred, non-pregnant and non-lactating cows were submitted to daily ultrasound-guided aspiration of follicles >6 mm (n = 10) or to sham aspirations (n = 8). Diameter of the largest follicle on the day of luteolysis (7.4 +/- 1.0 vs 9.7 +/- 1.0 mm; mean +/- SEM), number of days in which follicles >6 mm were present (2.3 +/- 0.4 vs 4.6 +/- 0.5 days) and daily mean diameter of the largest follicle between D15 and D19 (6.4 +/- 0.2 vs 8.5 +/- 0.3 mm) were smaller (p <0.01) in the aspirated group compared with the control group, respectively. Aspiration tended to reduce (p< 0.10) plasma estradiol concentrations between D18 and D20 (2.95 +/- 0.54 vs 4.30 +/- 0.55 pg/ml). The luteal lifespan was similar (p > 0.10) between the groups (19.6 +/- 0.4 days), whereas the oestrous cycle was longer (p <0.01) in the aspirated group (31.4 +/- 1.2 vs 21.2 +/- 1.3 days). Hyperechogenic structures were present at the sites of aspiration and were associated with increase in concentration of progesterone between luteolysis and oestrus. It is concluded that follicular aspiration extended the oestrous cycle and decreased the average follicular diameter on the peri-luteolysis period but failed to delay luteolysis.

Effects of flavomycin on ruminal fermentation, In situ degradability and In vivo digestibility in bovine fed sugarcane diets

Problem statement: The aim of the present study was to characterize and differentiate the effects of addition of flavomycin or monensin on ruminal fermentation and degradability as well as on total digestibility in bovine. Approach: Twelve non-pregnant and non-lactating cows (736 kg of BW) were randomly assigned to three treatments: control, flavomycin (20 mg animal-1 day-1) and monensin (300 mg animal-1 day-1). The trial lasted 21 days. The last 10 days were used for external marker administration (15 g of chromic oxide animal-1 day-1). The last 5 days of the trial were used for feces collection and evaluation of corn grain, soybean meal or sugarcane ruminal degradability and the 21st day was used for ruminal fluid sampling. Results: Monensin increased 27.2%, on average, propionate molar proportion at 0, 4, 6, 8, 10 and 12 h after feeding, compared to control and flavomycin groups. When compared to control, flavomycin reduced the degradation rate of soybean meal CP in 31.0%, decreasing the effective degradability when passage rates of 5 and 8% h-1 were used. Dry matter intake, pH, total Short Chain Fatty Acids (tSCFA) or ammoniacal Nitrogen (NH3-N) concentration were not influenced by the addition of either antibiotics. Effective degradability of sugarcane NDF was not influenced by the use of either antibiotic; neither were the TDN nor the digestibility of DM, CP, EE, NFE, ADF, NDF, GE or starch of the diet. Conclusion/Recommendations: In the present study, it was possible to show the beneficial effects of monensin but not of flavomycin, on rumen fermentation

Effect of nAellore cows ciclicity on conception and pregnant rates after synchronization protocols for fixed timed artificial insemination

Palhano H.B., Jesus V.L.T., Abidu-Figueiredo M., Baldrighi J.M. & Mello M.R.B. [Effect of nAellore cows ciclicity on conception and pregnant rates after synchronization protocols for fixed timed artificial insemination]. Efeito da ciclicidade de vacas Nelore sobre as taxas de concepcao e de prenhez apos protocolos de sincronizacao para inseminacao artificial em tempo fixo. Revista Brasileira de Medicina Veterinaria, 34(1):63-68, 2012. Departamento de Biologia Animal, Universidade Federal Rural do Rio de Janeiro, BR 465 km 7, Seropedica, RJ 23890-000, Brasil. Email: hbpalhano@gmail.com The present study evaluated the effect on conception and pregnancy rates of Nellore cows selected for Fixed Timed Artificial Insemination (FTAI) program, submitted to four synchronization protocols. Four hundred and ninety lactating females were used and assigned to eight groups: I-OvSynch, n=68, with selection of cycling cows; II-OvSynch + progesterone (P-4), n=67, after selection of non-cycling animals; III-OvSynch, without selection, n=68; IV-OvSynch + P-4, without selection, n=67; V-Co-Synch, n=55, with selection of cycling cows; VI-Co-Synch + P-4, n=55, with selection non-cycling cows; VII- Co-Synch without selection, n=55; VIII- Co-Synch + P-4, without selection, n=55. The conception and pregnancy rates were, respectively, 45.6%, 27.9% and 82.4%, 48.5% for groups I and III; 61.2%, 37.3% and 85.1%, 58.2% for groups II and IV; 43.6%, 25.5% and 80%, 41.8% for groups V and VII; 52.7%, 32.7% and 83.6%, 50.9% for groups VI and VIII. When compared these rates, the results after chi-square test showed significant difference (P < 0.05) among protocols with or without selection. There was no significant difference (P > 0.05) between OvSynch and Co-Synch protocols, with or without P-4 and with selection, considering Co-Synch a viable option for optimization of FTAI. In conclusion, the selection of cows before FTAI program contributed significantly to improve the conception and pregnancy rates.

Effects of two estradiol esters (benzoate and cypionate) on the induction of synchronized ovulations in Bos indicus cows submitted to a timed artificial insemination protocol

The effects of estradiol benzoate (EB) and estradiol cypionate (EC) on induction of ovulation after a synchronized LH surge and on fertility of Bos indicus females submitted to timed AI (TAI) were evaluated. In Experiment 1, ovariectomized Nelore heifers were used to evaluate the effect of EB (n = 5) and EC (n = 5) on the circulating LH profile. The LH surge timing (19.6 and 50.5 h; P = 0.001), magnitude (20.5 and 9.4 ng/mL; P = 0.005), duration (8.6 and 16.5 h; P = 0.001), and area under the LH curve (158.6 and 339.4 ng/mL; P = 0.01) differed between the EB and EC treatments, respectively. In Experiment 2 (follicular responses; n = 60) and 3 (pregnancy per AI; P/AI; n = 953) suckled Bos indicus beef cows submitted to an estradiol/progesterone-based synchronization protocol were assigned to receive one of two treatments to induce synchronized ovulation: 1 mg of EB im 24 h after progesterone (P4) device removal or 1 mg of EC im at P4 device removal. There was no difference (P > 0.05) between EB and EC treatments on follicular responses (maximum diameter of the ovulatory follicle, 13.1 vs. 13.9 mm; interval from progesterone device removal to ovulation, 70.2 vs. 68.5 h; and ovulation rate, 77.8 vs. 82.8%, respectively). In addition, P/AI was similar (P < 0.22) between the cows treated with EB (57.5%; 277/482) and EC (61.8%; 291/471). In conclusion, despite pharmacologic differences, both esters of estradiol administered either at P4 device removal (EC) or 24 h later (EB) were effective in inducing an LH surge which resulted in synchronized ovulations and similar P/AI in suckled Bos indicus beef cows submitted to TAI. (C) 2012 Elsevier Inc. All rights reserved.

Manipulation of follicle development to ensure optimal oocyte quality and conception rates in cattle

Over the last several decades, a number of therapies have been developed that manipulate ovarian follicle growth to improve oocyte quality and conception rates in cattle. Various strategies have been proposed to improve the responses to reproductive biotechnologies following timed artificial insemination (TAI), superovulation (SOV) or ovum pickup (OPU) programmes. During TAI protocols, final follicular growth and size of the ovulatory follicle are key factors that may significantly influence oocyte quality, ovulation, the uterine environment and consequently pregnancy outcomes. Progesterone concentrations during SOV protocols influence follicular growth, oocyte quality and embryo quality; therefore, several adjustments to SOV protocols have been proposed depending on the animal category and breed. In addition, the success of in vitro embryo production is directly related to the number and quality of cumulus oocyte complexes harvested by OPU. Control of follicle development has a significant impact on the OPU outcome. This article discusses a number of key points related to the manipulation of ovarian follicular growth to maximize oocyte quality and improve conception rates following TAI and embryo transfer of in vivo-and in vitro-derived embryos in cattle.

Heritability Estimate and Genetic Correlations of Reproductive Features in Nellore Bulls, Offspring of Super Precocious, Precocious and Normal Cows Under Extensive Farming Conditions

The present work aimed to estimate heritability and genetic correlations of reproductive features of Nellore bulls, offspring of mothers classified as superprecocious (M1), precocious (M2) and normal (M3). Twenty one thousand hundred and eighty-six animals with average age of 21.29 months were used, evaluated through the breeding soundness evaluation from 1999 to 2008. The breeding soundness features included physical semen evaluation (progressive sperm motility and sperm vigour), semen morphology (major, minor and total sperm defects), scrotal circumference (SC), testicular volume (TV) and SC at 18 months of age (SC18). The components of variance, heritability and genetic correlations for and between the features were estimated simultaneously by restricted maximum likelihood, with the use of the vce software system vs 6. The heritability estimates were high for SC18, SC and TV (0.43, 0.63 and 0.54; 0.45, 0.45 and 0.44; 0.42, 0.45 and 0.41, respectively for the categories of mothers M1, M2 and M3) and low for physical and morphological semen aspects. The genetic correlations between SC18 and SC were high, as well as between these variables with TV. High and positive genetic correlations were recorded among SC18, SC and TV with the physical aspects of the semen, although no favourable association was verified with the morphological aspects, for the three categories of mothers. It can be concluded that the mothers sexual precocity did not affect the heritability of their offspring reproduction features.

Comparison of ultrasonography and histopathology for the diagnosis of endometritis in Holstein-Friesian cows

Reproductive diseases are a great barrier to dairy production, as they diminish fertility and cause economic loss. In this context, endometritis plays an important role. Different diagnostic techniques exist for endometritis that vary in sensitivity and specificity. This work aimed to evaluate and compare ultrasonographic and histopathological examinations, and combinations thereof, for the diagnosis of endometritis by determining their sensitivity, specificity, and kappa agreement coefficients using endometrial cytology as the gold standard. We developed an adaptive reading score to perform histological examination of the uterus. In this study, 76 Holstein-Friesian cows, 21 to 47 d postpartum, without vaginal catarrh were submitted to gynecological examinations, including ultrasonographic examination, an endometrial cytology examination, and a uterine biopsy. Our results indicate that ultrasonography is a practical and effective diagnostic method, and a combination of the determination of intrauterine fluid and cervical diameter was the most efficient ultrasonographic method, with 50% sensitivity and 88% specificity. Histopathological examination was a useful diagnostic method that provided rich detail on endometrial inflammation, and allowed evaluation of different components of the tissue such as the epithelium, lamina propria, endometrial glands, and blood vessels; this method had 44% sensitivity and 92% specificity for diagnosis of endometritis.

ERYTHROGRAM PROFILE DURING POSTPARTUM PERIOD IN HOLSTEIN COWS

With the intention to evaluate the erythrogram profile during postpartum period in Holstein cows, 142 blood samples were collected from cows during the first 90 days after parturition. Blood samples were collected from clinically healthy cows that were non-reactive to the antigen of bovine leukosis virus (GP 51). These animals were divided into nine experimental groups based on the time of the postpartum sample collection. The blood samples were collected with EDTA and submitted to the following tests: erythrocyte counts, packed cell volume, hemoglobin concentration and calculated blood indices (MCV, MCH, MCHC). There was influence of the postpartum period on the erythrogram. These alterations were observed during the first 24 h after parturition. The hemoconcentration observed during the parturition disappeared during the first 24h of postpartum. Variation of the values were observed: red blood, 5.08 +/- 0.60 and 6.11 +/- 0.72 cells /mu L; hemoglobin concentration, 9.85 +/- 1.6 and 11.46 +/- 1,40 g/dL; packed cell volume, 27.9 +/- 3.3 and 31.9 +/- 3.6 %; MVC, 50.10 +/- 5.90 and 55.27 +/- 6.88 fL; MHC, 18.19 +/- 1.63 and 19.50 +/- 2.76 pg; MCHC, 34.83 +/- 2.07 and 36.88 +/- 1.67 %. The values of the hematological components obtained in this study did not exceed the limits of the reference values, obtained from cows raised within the state of Sao Paulo.

Quality and quantity of milk produced by Saanen goats submitted to stress during three sequential days

The experiment aimed to study the effect of physiological stress on cortisol levels, quality and quantity of milk through punctual administration of ACTH. Twelve Saanen goats were divided in two experimental groups: ACTH group (0,5 mu g of ACTH/Kg.L.W); Placebo group (placebo solution). Milk production, and percentages of protein, fat, lactose and SCC (somatic cells counting) of the milk were analyzed before, during and after the administration of ACTH/placebo. Simultaneously to the ACTH/placebo administration and during three sequential days, blood was collected to evaluate cortisol concentrations. At times -30 and zero, both groups presented basal concentrations of cortisol. The increase of cortisol contents was significant at times 60 (group ACTH: 59.00 +/- 5.70 and groups placebo: 5.23 +/- 1.37ng/mL) and 120 (group ACTH: 47.96 +/- 9.72 and group placebo: 4.38 +/- 1,14ng/mL) since the cortisol content was higher on the ACTH group. The values returned to the basal level at 300 minutes. Concerning milk production, no differences were found between ACTH and placebo groups. Milk, protein, fat, lactose and SCC did not distinguish one group from another. The results indicated that the physiological stress induced during three days was not harmful to milk production and milk quality of Saanen goats.

Intracellular Reactive Oxygen Species Production by Polymorphonuclear Leukocytes in Bovine Leukemia Virus-Infected Dairy Cows

The present study assesses the oxidative burst activity from polymorphonuclear leukocytes (PMNLs) from bovine leukemia virus (BLV)-infected cows. Fifteen clinically healthy cows were divided into serologically positive cows without any hematological alteration, serologically positive animals with persistent lymphocytosis (PL) and healthy serologically negative cows. The oxidative burst activity from the PMNLs was evaluated by now cytometry using 2',7'-dichlorofluorescein diacetate as a probe. PMNLs from each cow were incubated with heat-killed Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) to stimulate oxidative burst activity. The results of the present work showed no significant difference in the oxidative burst activity without any stimulus and elicited by S. caucus. Conversely, a decrease in the oxidative burst index induced by E. coli in PMNLs was observed in BLV-infected cows.

Quantification of B cells and T lymphocyte subsets in bovine leukemia virus infected dairy cows

The aim of the present trial was to determine the frequencies and absolute number of B and T lymphocytes subpopulations in bovine leukemia virus (BLV)-infected dairy cows with distinct lymphocyte profile known as non-leukemic (AL) and persistent lymphocytosis (PL). Thus, 15 animals were selected and divided uniformly in three groups (negative, AL, PL). The BLV infection was detected by agar gel immunodiffusion and enzyme-linked immunosorbent-assay. The lymphocytes subsets were evaluated using monoclonal antibodies by flow cytometry. The results of the present study pointed out to an increase in B lymphocytes, and also an augment in CD5(+) and CD11b(+) cells in animals showing PL. Consequently, it can be observed a decrease in the percentage of T cells subsets in these animals. Conversely, no significant alterations in the absolute number of the T lymphocytes, T CD4(+) cells and T CD8(+) lymphocytes were found in BLV-infected dairy cows with PL. Therefore, the correlation between the absolute numbers of B- and T cell subsets in the peripheral blood applied to each group showed a significant and positive strong correlation between numbers of B cells and T cells or T CD8(+) cells in the PL animals, although the same cannot be predicted for T CD4(+) lymphocytes. No such correlation was encountered for the AL and negative-control animals.

Assessment of field fertility and several in vitro sperm characteristics following the use of different Angus sires in a timed-AI program with suckled Nelore cows

In order to provide information that may help researchers to understand the main cause(s) of differences in bull fertility frequently observed in field trials, this study aimed to investigate conception rates as well as several in vitro sperm characteristics of different sires of unknown fertility utilized in a Timed-AI (TAI) program. Suckled Nelore cows submitted to the same TAI protocol were allocated into eight breeding groups of approximately 120 animals each. Frozen semen doses from three Angus bulls and three different batches from each bull were utilized. Approximately 100 doses from each batch were used in TAI. Sires, batches and AI technicians were equally distributed across breeding groups. Cows were examined for pregnancy diagnosis 40 d after TAI. For in vitro sperm analyses, the same thawing procedure was repeated in the laboratory to mimic field conditions. The following in vitro sperm characteristics were assessed: computerized motility, thermal resistance, plasma and acrosomal membrane integrity, lipid peroxidation, morphology, morphometry and chromatin structure. No effect of breeding group, body condition score, AI technician and sire was observed. However, some significant differences among bulls were detected in laboratory analyses. Semen from sire presenting numerically lower (P > 0.05) pregnancy/AI also presented lower (P < 0.05) values in all sperm characteristics analyzed in thermal resistance test at 4 h (Total Motility, Progressive Motility, Average Path Velocity, Straight-Line Velocity, Curvilinear Velocity, Amplitude of Lateral Head Displacement, Beat Cross Frequency, Straightness, Linearity, and Percentage of Rapidly Moving Cells), higher (P < 0.05) Major and Total Defects in sperm morphological test, lower (P < 0.05) Length, Ellipticity and Fourier parameter (Fourier 0) in sperm morphometric analysis as well as higher (P < 0.05) chromatin heterogeneity. It was concluded that, although no bull effect was observed in the field experiment, the sire that presented numerically lower pregnancy/AI also presented lower semen quality according to the laboratory analyses performed. (C) 2012 Elsevier B.V. All rights reserved.

Effect of sequence of insemination after simultaneous thawing of multiple semen straws on conception rate to timed AI in suckled multiparous Nelore cows

The objective was to determine the effect of sequence of insemination after simultaneous thawing of multiple 0.5 mL semen straws on conception rate in suckled multiparous Nelore cows. The effect of this thawing procedure on in vitro sperm characteristics was also evaluated. All cows (N = 944) received the same timed AI protocol. Ten straws (0.5 mL) of frozen semen from the same batch were simultaneously thawed at 36 degrees C, for a minimum of 30 sec. One straw per cow was used for timed AI. Frozen semen from three Angus bulls was used. Timed AI records included sequence of insemination (first to tenth) and time of semen removal from thawing bath. For laboratory analyses, the same semen batches used in the field experiment were evaluated. Ten frozen straws from the same batch were thawed simultaneously in a thawing unit identical to that used in the field experiment. The following sperm characteristics were analyzed: sperm motility parameters, sperm thermal resistance, plasma and acrosomal membrane integrity, lipid peroxidation, chromatin structure, and sperm morphometry. Based on logistic regression, there were no significant effects of breeding group, body condition score, AI technician, and sire on conception rate, but there was an interaction between sire and straw group (P = 0.002). Semen from only one bull had decreased (P < 0.05) field fertility for the group of straws associated with the longest interval from thawing to AI. However, the results of the laboratory experiment were unable to explain the findings of the field experiment. Sperm width:length ratio of morphometric analysis was the single sperm characteristic with a significant interaction between sire and straw group (P = 0.02). It was concluded that sequence of insemination after simultaneous thawing of 10 semen straws can differently affect conception rates at timed AI, depending on the sire used. Nevertheless, the effects of this thawing environment on in vitro sperm characteristics, remain to be further investigated. (C) 2012 Elsevier Inc. All rights reserved.

Organic and inorganic sources of zinc, copper and selenium in diets for dairy cows: intake, blood metabolic profile, milk yield and composition

The present study was carried out with the objective of evaluating the effects of feeding dairy cows with organic or inorganic sources of zinc (Zn), copper (Cu) and selenium (Se) on blood concentrations of these minerals, blood metabolic profiles, nutrient intake and milk yield and composition. Nineteen Holstein cows were selected and randomly assigned to two groups for receiving organic (n = 9) or inorganic (n = 10) sources of Zn, Cu and Se from 60 days before the expected date of calving to 80 days of lactation. Samples of feed, orts and milk were collected for analysis. Body condition score (BCS) was determined and blood samples were collected for analysis of Zn, Cu and Se concentrations, as well as for metabolic profile. Supplying organic or inorganic sources of Zn, Cu, and Se did not affect dry matter and nutrient intake, blood metabolic profile, milk yield and composition, plasma concentration of these minerals, and BCS or change the BCS in cows from 60 days before the expected date of calving to 80 days of lactation. An effect of time was observed on all feed intake variables, plasma concentrations of Zn and Se, milk yield, milk protein content, BCS and change in BCS.