Genetic relationship among reproductive traits in Nellore cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of polyethylene film wrap on cooler shrink and the microbial status of beef carcasses

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Index of thermal stress for cows (ITSC) under high solar radiation in tropical environments

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Genetic associations between temperament and performance traits in Nellore beef cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genetic analysis for gestation length, birth weight, weaning weight, and accumulated productivity in Nellore beef cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of supplementation frequency on the ruminal fermentation and enteric methane production of beef cattle grazing in tropical pastures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Plasma concentrations of progesterone, 17 beta-estradiol and androstenedione and superovulatory response of nelore cows (Bos indicus) treated with FSH

Progesterone (P-4), 17 beta- estradiol (E2) and androstenedione (A4) plasma concentrations were correlated with palpated corpora lutea (CL), recovered embryos and viable embryos in 13 Nelore cows induced to superovulate with FSH, starting on Day 10 of the estrous cycle. Administration of FSH increased the number of ovulations and recovered embryos. Plasma P4, E2 and A4 levels on Day O and of P4 on Days 10 and 11 of the cycle were not correlated with the superovulatory response. Determination of CL by palpation per rectum was used to estimate the number of recovered embryos. Plasma P4 levels higher than 1 ng/ml on the induced estrus day (Day 14) had an adverse effect on the embryo viability rate. Plasma E2 concentrations on Day 14 were positively correlated with the number of viable embryos collected, a correlation that has not been previously reported. The present data indicate that plasma P4 and E2 concentrations in FSH-PGF2 alpha-treated Nelore cows are useful for the identification of 2 different populations of Nelore donors and are correlated with superovulatory response and, particularly, with the number of viable embryos.

Efficiency of superstimulatory protocol P-36 associated with the administration of eCG and LH in Nelore cows

Recent work with P-36 demonstrates that the replacement of the last two doses of Follicle-Stimulating Hormone (FSH) with equine chorionic gonadotropin (eCG) increases embryo yields. However, it is unclear if the positive effect of eCG is related to its FSH-like activity, LH-like activity, or both. This study aimed to verify the replacement of eCG with pLH on the last day of superstimulatory treatment. Twenty-five Nelore cows were allocated to four groups: P-36 (control), P-36/eCG, P-36/LH2, and P-36/LH4. All animals underwent four treatments in a crossover design. The control group cows were superstimulated with decreasing doses of porcine Follicle-Stimulating Hormone (pFSH, 133 mg, im). In the P-36/eCG, P-36/LH2, and P-36/LH4 groups, the last two doses of pFSH were replaced in the former group by two doses of eCG (200 IU each dose, im) and in the latter two groups by two doses of pLH (1 and 2 mg each dose, im), respectively. Donors received fixed-time artificial insemination 12 and 24 hours after pLH. Embryo flushing was performed on D16. Data were analyzed by ANOVA (Proc Mixed, SAS). There was a trend of decreasing ovulation rate when comparing groups LH2 and eCG (P = 0.06). However, there was no significant difference in the mean number of viable embryos among groups P-36 (3.3 ± 0.7), P-36/eCG (4.5 ± 0.5), P-36/LH2 (3.7 ± 0.8), and P-36/LH4 (4.2 ± 1.0). It is concluded that the replacement of eCG by pLH on the last day of superstimulatory treatment can be performed with no significant variation in the production of viable embryos.

Utility of inline milk fat and protein ratio to diagnose subclinical ketosis and to assign propylene glycol treatment in lactating dairy cows

The objective was to identify a fat-to-protein ratio (FPR) cut-off to diagnose subclinical ketosis (SCK) and to evaluate the effect of propylene glycol (PPG) treatment of cows with high FPR. The optimized cut-off was > 1.42; sensitivity (Se) = 92%; specificity (Sp) = 65%. A cut-off > 1.5 was selected for the PPG trial for balanced Se-Sp. Fat-to-protein ratio cut-offs > 1.25, 1.35, 1.50, 1.60, and 1.70 resulted in Se-Sp of 100% to 49%, 96% to 59%, 75% to 78%, 33% to 90%, and 8% to 96%, respectively. The proportions of cows with FPR > 1.25, 1.35, 1.42, 1.50, 1.60, and 1.70 were 60%, 50%, 44%, 30%, 14%, and 6%, respectively. Incidences of clinical ketosis and milk yield were similar between cows that received 400 mL of PPG (n = 34) and control cows (n = 38). Prevalence of SCK at enrollment was 29.2%; therefore, FPR > 1.5 is not indicated for treatment. Lower cut-offs should be used for screening.

Effect of essential oils of Syzygium aromaticum and Cinnamomum zeylanicum and their major components on biofilm production in Staphylococcus aureus strains isolated from milk of cows with mastitis

Bovine mastitis is an inflammation of the mammary glands of cows and causes significant economic losses in dairy cattle. Staphylococcus aureus is one of the microorganisms most commonly isolated. Novel agents are required in agricultural industries to prevent the development of mastitis. The production of biofilm by Staph. aureus facilitates the adhesion of bacteria to solid surfaces and contributes to the transmission and maintenance of these bacteria. The effect of the essential oils of Syzygium aromaticum (clove; EOSA) and Cinnamomum zeylanicum (cinnamon; EOCZ) and their major components, eugenol and cinnamaldehyde, on Staph. aureus biofilm formation on different surfaces was investigated. The results showed a significant inhibition of biofilm production by EOSA on polystyrene and stainless steel surfaces (69.4 and 63.6%, respectively). However, its major component, eugenol, was less effective on polystyrene and stainless steel (52.8 and 19.6%, respectively). Both EOCZ and its major component, cinnamaldehyde, significantly reduced biofilm formation on polystyrene (74.7 and 69.6%, respectively) and on stainless steel surfaces (45.3 and 44.9%, respectively). These findings suggest that EOSA, EOCZ, and cinnamaldehyde may be considered for applications such as sanitization in the food industry.

Comparative efficacy of exogenous eCG and progesterone on endogenous progesterone and pregnancy in Holstein cows submitted to timed artificial insemination

Coordenação de Apoio de Pessoal de Nível Superior (CAPES)

First genetic identification of Cryptosporidium parvum subtype IIaA14G2R1in beef cattle in Brazil

The presence of Cryptosporidium spp. in a cattle herd registered with an outbreak of diarrhea was investigated and the the molecular subtyping of Cryptosporidium parvum was characterized. Fecal samples from 85 Nellore beef cattle (Bos indicus) were collected and examined with Ziehl-Neelsen modified staining method. Fifty-four cattle (63.52%) had Cryptosporidium spp. oocysts in their feces. Fragments of genes encoding the 18S ribosomal RNA subunit and a 60-kDa glycoprotein (gp60) were amplified by nested PCR accomplished in the 11 most heavily parasitized samples, and the amplicons were sequenced. Eight of the 11 analyzed samples were positive for 18S rRNA sequences and identified monospecific infections with C. parvum. Seven samples were positive for gp60 and identified subtypes IIaA15G2R1 (6/11) and IIaA14G2R1 (1/11). This report is the first for C. parvum subtype IIaA14G2R1 in beef cattle in Brazil.

Reproductive efficiency of Nellore cows nursing Nellore or crossbred Simmental x Nellore calves

The objective of this study was to analyze the influence of genetic group (GG) of the calf during gestation, mobilization of body reserves and period of postpartum anestrus in Nellore cows. Thirty-seven primiparous and multiparous cows were used: 24 gave birth to Nellore (NEL), and 13 gave birth to 1/2 Simmental x 1/2 Nellore (SIM) calves. According to the date of calving, cows were divided into three blocks, with intervals of 20 days between blocks. The body condition (BC) of the cows was estimated subjectively on a scale from 0 to 5 points, with intermediate grading of 0.5 points. We measured the thickness of subcutaneous fat (SF) between the 12th and 13th ribs and rump by ultrasound. Blood samples from each cow were collected weekly from the third week after birth until weaning, to analyze the level of progesterone; in the samples collected until 16 weeks postpartum, we analyzed the concentration of nonesterified fatty acids(NEFA). The gestation period of mothers of NEL calves was eight days longer, on average. The variables relating to the mobilization of body reserves (NEFA, BC and SF) were not influenced by calf GG, with the only significant effects being the number of days postpartum, witha peak in the concentration of NEFA between the sixth and eighth weeks and linear decrease in BC and NF. Mothers of NEL calves remained in anestrus for 4.6 weeks longer than the mothers of crossbred calves.

Management of age at puberty in beef heifers to optimize efficiency of beef production

Age at puberty in beef heifers can influence economic efficiency of beef production through effects on both age at first calving (2 vs. 3+ years of age) and the time of conception of heifers in their initial breeding season. An overarching factor that influences age at puberty in heifers is nutritional management during both the preweaning period and between weaning and the breeding season. Age at puberty is heritable and selection for precocious puberty in populations such as the Nelore breed has the potential to substantially influence production efficiency. Highly effective hormonal technologies exist to aid in induction of puberty in well managed heifers. Age at first ovulation and pregnancy in heifers can be substantially influenced through implementation of nutritional and/or hormonal manipulation strategies. In the long term, combinations of genetic selection, nutritional strategies, and hormonal intervention when necessary will optimize efficiency of this aspect of beef production.

Influence of lineage of oocyte donor on the yield and morphology of oocytes recovered by ultrasound-guided follicular aspiration in nellore cows

The objective of this study was to investigate the influence of lineage of oocytes donors on the number and quality of oocytes obtained through ultrasound-guided follicular aspiration in Nellore breed cows derived from two lineages of bulls (Karvadi; K and Taj-Mahal; T). Both maternal (Km and Tm) and paternal (Kp and Tp) lineages, as well as their combinations were investigated. Oocyte aspirations were repeatedly performed with an aspiration interval of 15 days in 56 donor females. Recovered cumulus oocyte-complexes (COCs) were counted, morphologically examined and classified into seven categories (grades from I to VII) according to the number of layers of the cumulus oocyte and cytoplasm appearance. The mean number of oocytes retrieved from donors of lineage Tp-Tm was significantly higher (28.23±1.92, P<0.05) than those obtained from lineages Kp-Tm, Kp-Km, and Tp-Km (21.34±1.32, 21.28±1.73, and 16.72±1.31, respectively). There was no significant difference in the mean number of recovered oocytes between donors of lineages Kp-Km and Kp-Tm, whereas animals of lineage Tp-Km yielded the lowest number of oocytes. Higher mean number of grade III oocytes was recovered from donors of lineage Kp than lineage Tp (10.11±0.66 versus 8.79±0.58, respectively), with more grade III oocytes being obtained in both lineages as compared to the others. Paternal lineage did not influence the quality of recovered oocytes in any other category, but both Kp and Tp yielded a great mean number of oocytes graded as I, II, and III (3.14±0.21; 4.93±0.33, and 10.11±0.66 versus 3.19±0.21, 5.59±0.44, and 8.79±0.58, respectively) than those classified as IV, V, VI, and VII. However, when considering the data from the maternal lineage significantly more oocytes (P<0.05) of grade I, II and III were obtained from Taj-Mahal (11.67 ± 0.67, 5.9±0.42 and 3.64±0.25, respectively) than for lineage Karvadi, with similar results for oocytes of grades IV, V, VI, and VII. Similarly to the paternal lineage, the number of oocytes of grade III was superior (P<0.05) when compared to other categories for both lineages. In conclusion, we demonstrate here a direct influence of lineage of oocyte donor on the production and quality of oocytes obtained through ultrasound-guided follicular aspiration in Nellore cows.