Effect of single nucleotide polymorphisms of CAPN1 and CAST genes on meat traits in Nellore beef cattle (Bos indicus) and in their crosses with Bos taurus

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

Assessment of GH1, CAPN1 and CAST polymorphisms as markers of carcass and meat traits in Bos indicus and Bos taurus-Bos indicus cross beef cattle

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

Detection of Babesia bigemina in cattle of different genetic groups and in Rhipicephalus (Boophilus) microplus tick

Babesia bigemina infections were investigated in four genetic groups of beef cattle and in Rhipicephalus (Boophilus) microplus engorged female ticks. Blood samples and engorged female ticks were collected from 15 cows and 15 calves from each of the following genetic groups: Nelore, Angus x Nelore, Canchim x Nelore, and Simmental x Nelore. Microscopic examination of blood smears and tick hemolymph revealed that merozoites of B. bigemina (6/60) as well as kinetes of Babesia spp. (9/549) were only detected in samples (blood and ticks, respectively) originated from calves. PCR-based methods using primers for specific detection of B. bigemina revealed 100% infection in both calves and cows, regardless the genetic group. Tick infection was detected by nested-PCR amplifications showing that the frequency of B. bigemina was higher (P 0.01) in female ticks collected from calves (134/549) than in those collected from cows (52/553). The frequency of B. bigemina was similar in ticks collected from animals, either cows or calves, of the four genetic groups (P > 0.05). (C) 2008 Elsevier B.V. All rights reserved.

Associations between LEP, DGAT1 and FABP4 gene polymorphisms and carcass and meat traits in Nelore and crossbred beef cattle

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

Growth and carcass traits associated with GH1/Alu I and POU1F1/Hinf I gene polymorphisms in Zebu and crossbred beef cattle

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

Growth hormone 1 gene (GH1) polymorphisms as possible markers of the production potential of beef cattle using the Brazilian Canchim breed as a model

The growth hormone 1 gene (GH1) is a candidate gene for body weight and weight gain in cattle since it plays a fundamental role in growth regulation. We investigated the GH1 gene AluI and DdeI restriction enzyme polymorphisms, located 149 bp apart in the cattle genome, as possible markers of the production potential of Canchim crossbreed cattle, a 5/8 Charolais (Bos taurus) and 3/8 Nelore (Bos indicus) breed developed in Brazil, by evaluating the birth weight, weaning weight, yearling weight and plasma insulin-like growth factor-1 (IGF-1) concentration of 7 month to 10 months old Canchim calves (n = 204) of known genealogy and which had been genotyped for the AluI and DdeI markers. Our results showed significant effect (p < 0.05) between the homozygous DdeI+/DdeI+ polymorphism and the estimated breeding value for weaning weight (ESB-WW), while the AluI leucine homozygous (L/L) and leucine/valine (L/V) heterozygous polymorphisms showed no significant effect on the traits studied. The restriction sites of the two enzymes led to the formation of haplotypes which also exerted a significant effect (p < 0.05) on the ESB-WW, with the largest difference being 8.5 kg in favor of the homozygous L plus DdeI+/L plus DdeI+ genotype over the heterozygous L plus DdeI-/V plus DdeI+ genotype.

Genetic parameter estimates and response to selection for weight and testicular traits in Nelore cattle

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Feedlot performance, feed efficiency and carcass traits in Nellore cattle selected for postweaning weight

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

Genetic polymorphisms related to meat traits in purebred and crossbred Nelore cattle

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

Development of estrous synchronization protocols using melengestrol acetate in Bos indicus cattle

Five experiments were conducted on commercial farms in Brazil designed to develop the basis for an estrus synchronization protocol using melengestrol acetate (MGA) in Bos indicus cattle. These studies resulted in the development of the following protocol: 0.5 mg.d(-1) of MGA between d -14 and -1; 2.0 mg i.m. injection of estradiol cypionate on d -9; 48 h temporary weaning between d 0 and 2; and natural service beginning on d 0. The basis of this protocol was to induce estrous cyclicity before postpartum loss of body condition, prevent premature luteolysis, eliminate the need for labor required to detect estrus, and consequently increase the likelihood of pregnancy early during the postpartum period. This treatment effectively induced estrous cyclicity among anestrous cows, synchronized estrus activity, and prevented premature luteolysis with no negative effect on pregnancy.

Effects of fetuin on zona pellucida hardening, fertilization and embryo development in cattle

Mammalian oocytes can undergo spontaneous meiotic maturation when they are liberated from their follicles and cultured in vitro; however, the zona pellucida (ZP) becomes resistant to chymotrypsin digestion, or hardens, when spontaneous maturation occurs in serum-free medium. Schroeder et al. [Biol. Reprod. 43 (1990) 891] described that fetuin, a component of fetal calf serum (FCS), inhibits ZP hardening during oocyte maturation. The aim of this experiment was to study the effect of the presence of cumulus cells and addition of hormones to maturation media on bovine zona hardening and embryo development in medium with and without fetuin. In Experiment 1, different concentrations of fetuin were added to the maturation medium. The time necessary for digestion of 50% of the ZP (d50) was not different when oocytes were matured in presence of 10% FCS, 1 mg/ml polyvinyl alcohol (PVA), or 4, 1 and 0.25 mg/ml of fetuin; cleavage rates were also similar. However, significantly more blastocysts (P < 0.05) were formed when FCS was used compared to PVA and 0.25 mg/ml of fetuin. In Experiment 11, we examined the influence of the presence of cumulus cells and hormones during the maturation of oocytes in media with PVA, BSA, FCS and fetuin. The d50 was significantly higher (P < 0.05) when oocytes were matured in presence of cumulus cells. The cleavage rate of cumulus-intact oocytes was similar for all groups. However, when oocytes were partially stripped before maturation, the cleavage rate was significantly higher (P < 0.05) when FCS or fetuin was used. In both stripped and non-stripped groups, significantly more blastocysts (P < 0.05) were formed when oocytes were matured with FCS compared to BSA and PVA. These results indicate that zona hardening, as described for mouse and human oocytes, does not have a large effect on bovine cumulus-intact oocytes. Apparently fetuin can be used as a substitute for FCS during bovine oocyte maturation, since it leads to similar developmental rates as FCS in intact and partially stripped oocytes. (C) 2002 Published by Elsevier B.V. B.V.