The development of genomics applied to dairy breeding

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of pregnancy on the genetic evaluation of dairy cattle

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

Factors affecting fertilisation and early embryo quality in single- and superovulated dairy cattle

Data on fertilisation and embryo quality in dairy cattle are presented and the main factors responsible for the low fertility of single-ovulating lactating cows and embryo yield in superovulated dairy cattle are highlighted. During the past 50 years, the fertility in high-producing lactating dairy cattle has decreased as milk production increased. Recent data show conception rates to first service to be approximately 32% in lactating cows, whereas in heifers it has remained above 50%. Fertilisation does not seem to be the principal factor responsible for the low fertility in single-ovulating cows, because it has remained above 80%. Conversely, early embryonic development is impaired in high-producing dairy cows, as observed by most embryonic losses occurring during the first week after fertilisation. However, in superovulated dairy cattle, although fertilisation failure is more pronounced, averaging approximately 45%, the percentage of fertilised embryos viable at 1 week is quite high (>70%). Among the multifactorial causes of low fertility in lactating dairy cows, high feed intake associated with low concentrations of circulating steroids may contribute substantially to reduced embryo quality. Fertilisation failure in superovulated cattle may be a consequence of inappropriate gamete transport due to hormonal imbalances.

Genomic selection and assisted reproduction technologies to foster cattle breeding

Genomics has been propagated as a paradigm shifting innovation in livestock during the last decade. The possibility of predicting breeding values using genomic information has revolutionized the dairy cattle industry and is now being implemented in beef cattle. In this paper we discuss how genomics is changing cattle breeding through genomic selection, and how this change is creating new ways to articulate assisted reproduction technologies with animal breeding. We also debate that the scientific community is still starting the long journey to reveal the functional aspects of the cattle genome, and that knowledge in this field is the frontier to a whole new venue for the development of novel applications in the livestock sector.

Reference Gene Selection for Gene Expression Analysis of Oocytes Collected from Dairy Cattle and Buffaloes during Winter and Summer

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

Site and extent of amino acid digestion in dairy cattle fed with corn and its byproducts

The study was conducted to evaluated the site and extent of dry matter (DM), crude protein (CP), methionine (Met), lysine (Lys), and threonine (Thr) digestion of corn and byproducts obtained from corn germ mixed with different amounts of extruded or non-extruded ether extract (EE) in dairy cattle. Treatments consisted in eight types of feed and two processing in a 4 x 2 factorial design. There were four feeds: corn grain cracked (Corn), corn germ meal with 1% EE (CG1), corn germ meal with 7% EE (CG7), and corn germ meal with 10% EE (CG10). The feeds were processed in one of two ways: extruded (Ex) and not extruded. In situ techniques were used to determine DM, CP, Met, Lys, and Thr partial and total tract digestion. A basic diet was compounded of corn germ meal, soybean meal and coastcross hay in a 70: 30 roughage to concentrate ratio. There was no interaction (P>0.05) between feeds and processing method. Extrusion improved (P<0.05) total tract digestibility of corn DM but not CP. Intestinal digestibility was similar (P>0.05) for corn and corn germ meal mixed with 7 and 10% EE, regardless of EE processing method. The CP total tract digestibility of corn germ meal with 1% non-extruded EE was 16.62% higher (P<0.05) than that of the extruded form. The best total CP digestibility was obtained for corn germ meal with 7% EE, independently of the processing method. The effects of EE processing method on partial and total digestibility differed between amino acid. Corn and corn byproduct extrusion may improve dry matter digestibility, but do not necessarily influence crude protein digestion. Ruminal and intestinal digestibility of Met, Lys, and Thr depends on both feed type and processing method. Therefore, amino acid availability should be considered individually.

Reaction norm model to describe environmental sensitivity across first lactation in dairy cattle under tropical conditions

Reaction norm models have been widely used to study genotype by environment interaction (G × E) in animal breeding. The objective of this study was to describe environmental sensitivity across first lactation in Brazilian Holstein cows using a reaction norm approach. A total of 50,168 individual monthly test day (TD) milk yields (10 test days) from 7476 complete first lactations of Holstein cattle were analyzed. The statistical models for all traits (10 TDs and for 305-day milk yield) included the fixed effects of contemporary group, age of cow (linear and quadratic effects), and days in milk (linear effect), except for 305-day milk yield. A hierarchical reaction norm model (HRNM) based on the unknown covariate was used. The present study showed the presence of G × E in milk yield across first lactation of Holstein cows. The variation in the heritability estimates implies differences in the response to selection depending on the environment where the animals of this population are evaluated. In the average environment, the heritabilities for all traits were rather similar, in range from 0.02 to 0.63. The scaling effect of G × E predominated throughout most of lactation. Particularly during the first 2 months of lactation, G × E caused reranking of breeding values. It is therefore important to include the environmental sensitivity of animals according to the phase of lactation in the genetic evaluations of Holstein cattle in tropical environments.

Detection of antibodies against bovine respiratory syncytial virus (BRSV) in dairy cattle with different prevalences of bovine herpesvirus type 1 (BoHV-1) in São Paulo State, Brazil

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

Virulence Genes in Isolates of Escherichia coli from Samples of Milk and Feces from Dairy Cattle

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ruminal methane emission by dairy cattle in Southeast Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Genetic characterisation of Giardia duodenalis in dairy cattle in Brazil

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

Neospora caninum infection dynamics in dairy cattle

Neospora caninum is considered in many countries as one of the key abortion agents in cattle. This study aims to investigate the parasite behavior in dairy cattle in the municipality of Avar,, SP, Brazil, where abortions frequently occur. An ELISA was performed to compare two samplings on a total of 615 animals; tests were performed in the same herds with a gap of 3 years. An increase in the percentage of reactive animals was observed, ranging from 21.6% at the first sampling to 38.9% at the second sampling. of the 176 animals tested at both samplings, 61.93% retained a non-reactive status, 15.9% retained a reactive status, 19.88% switched from non-reactive to reactive and 2.27% switched from reactive to non-reactive. of the 100 animals with reproductive disturbances, 50% presented anti-Neospora antibodies, thereby indicating the presence of the protozoa. When comparing cows and their respective female offspring, a predominance of horizontal infection was observed. Moreover, considering the significant percentage of animals that switched from non-reactive to reactive and the abundant presence of dogs among the herds, the N. caninum transmission may be attributed to presence of carnivores.

First report of Trypanosoma vivax outbreak in dairy cattle in São Paulo state, Brazil

Esta é a primeira descrição de um surto de Trypanosomavivax ocorrido no Estado de São Paulo, no município de Lins. Animais acometidos apresentaram febre, icterícia, diminuição da produção de leite, perda de peso, diarreia profusa, abortos, anemia, leucocitose e hiperfibrigenemia. Foram registrados 31 óbitos de vacas e bezerros em 1.080 bovinos no total. Três vacas apresentaram sintomatologia nervosa, como dismetria, ataxia e fraqueza muscular, além de ptialismo, aumento de linfonodos e edema submandibular. Hemoparasitas flagelados foram observados em esfregaços sanguíneos, e a espécie de tripanossomo foi diagnosticada como T.vivax por PCR. A cepa de T. vivax mostrou ser resistente ao tratamento com aceturato de diaminozeno e a infecção disseminou rapidamente no rebanho. Pelo ELISA, observou-se que 98,36% (599) das amostras de soro colhidas apresentaram títulos positivos para IgG anti-T.vivax. O surto ocorreu em condições de baixa precipitação pluviométrica, fato que indica que outros fatores estavam envolvidos na ocorrência desse surto, como a ausência de tabanídeos e a grande presença de Haematobia irritans e Stomoxys calcitrans, cujo aumento populacional pode ser devido ao uso de resíduos de usinas de açúcar e álcool nos canaviais que circundavam a granja leiteira.

Prevalence of anti-Toxoplasma gondii antibodies in dairy cattle, dogs, and humans from the Jauru micro-region, Mato Grosso state, Brazil

In order to determine the prevalence of anti-Toxoplasma gondii antibodies, 2000 serum samples from female dairy cattle belonging to 50 farms in the southwest of Mato Grosso state were analyzed by the indirect fluorescent antibody test (IFAT >= 64). Serum samples from 61 dogs (IFAT >= 40) and 116 humans (IFAT = 40), all from the same farm, were also tested. Among these samples, 1420 (71.0%) cattle, 54 (88.5%) dogs, and 113 (97.4%) humans were seropositive for the infection. No significant differences (P >= 0.05) were observed for risk factors associated with the occurrence of toxoplasmosis in humans due to contaminated sources such as fresh milk, cheese/sausage, and contact with felines or other animals. The presence of felines can indicate the likelihood of a contaminated environment, posing a risk to the human population and other animals. The work presented herein is the first report to evaluate the seroprevalence of T gondii in bovines from the Southwest region of the Mato Grosso state, Brazil. (C) 2009 Elsevier B.V. All rights reserved.

Copper toxicosis in sheep fed dairy cattle ration in São Paulo, Brazil

Intoxicação crônica por cobre foi observada em um rebanho de 20 ovinos no município de Franca, São Paulo. Três meses após o início do arraçoamento com feno e ração concentrada peletizada para bovinos de leite, seis animais apresentaram anorexia, icterícia severa e urina marrom escura, e vieram a óbito. Diagnosticou-se doença hemolítica com base em sinais clínicos, alterações macroscópicas observadas na necropsia e observações histológicas. À necropsia todos os ovinos apresentaram icterícia severa, fígado amarelado com padrão lobular evidente e rins escuros. As principais alterações histológicas incluíram necrose hepática periacinar e nefrose hemoglobinúrica. Acúmulos de cobre foram demonstrados nos hepatócitos e macrófagos pela coloração rodamina e níveis elevados de cobre mediante espectrofotometria de absorção atômica no soro, fígado e rins de dois ovinos afetados e na ração fornecida.