Phenotypic variation in milk fatty acid composition and its association with stearoyl-CoA desaturase 1 (SCD1) gene polymorphisms in Gir cows.

Individual variation in milk fatty acid (FA) composition has been partially attributed to stearoyl-CoA desaturase 1 (SCD1) gene polymorphisms in taurine breeds, but much less is known for Zebu breeds. This study investigated the phenotypic variation in milk FA composition, and the influence of SCD1 variants on this trait and on milk fat desaturase indices (DI) in Gir cows. The functional impact of SCD1 variants was predicted using bioinformatics tools. Milk and blood samples were collected from 312 cows distributed in 10 herds from five states of Brazil. SCD1 variants were identified through target sequencing, and milk FA composition was determined by gas chromatography. Phenotypic variation in milk FA composition fell within the range reported for taurine breeds, with SCD18 index showing the lowest variation among the DI. Fourteen SCD1 variants were identified, six of which not previously described. Regarding the A293V polymorphism, all cows were homozygous for the C allele (coding for alanine), whereas all genotypes were detected for the second SNP affecting the 293 codon (G > A), with compelling evidence for functional effects. Significant associations (based on raw p-values) were found between this SNP and C12:0, cis-9, trans-11 CLA and short-chain FA, and between another SNP (rs523411937) and C15:0 and odd-chain linear FA. A new SNP on Chr26:21277069 was associated with trans-11 C18:1, cis-9, trans-11 CLA, C18:3 n-3 and n-3 FA. These findings indicate that SCD1 polymorphisms also contributes to the phenotypic variation in milk FA composition of Gir cows, with potential use in their breeding programmes.

Estratégias farmacológicas para a manipulação do ciclo estral de fêmeas bovinas de raças de corte taurinas / Pharmacological approaches to manipulate bovine estrous cycle in taurine beef breeds

Este texto discute as estratégias farmacológicas para a manipulação do ciclo estral de fêmeas taurinas de corte, com foco na inseminação artificial em tempo fixo (IATF). Os zebuínos, rebanho predominante no Brasil, apresentam características de ciclo estral diferentes das raças taurinas, o que justifica a busca por estratégias hormonais adaptadas para o controle do ciclo estral nas subespécies. O estradiol combinado com a progesterona (P4) e prostaglandina F2 alfa (PGF) é o esquema hormonal mais comumente utilizado para a manipulação do ciclo estral em protocolos de IATF. Porém, o uso de GnRH combinado ou em substituição aos ésteres de estradiol vem sendo considerado. Coletivamente, os dados do nosso grupo reforçam a necessidade de customizar as abordagens para o controle do ciclo estral de acordo com a composição genética das fêmeas bovinas.(AU)

This text discusses pharmacological strategies to manipulate the estrous cycle of taurine and synthetic females, with a focus on timed artificial insemination (TAI). Zebu cattle, the predominant herd in Brazil, have different estrous cycle characteristics than taurine breeds, requiring different synchronization hormonal strategies for each subspecies. Estradiol combined with progesterone (P4) and prostaglandin F2 alpha (PGF) is the most used hormonal scheme for estrous cycle manipulation in TAI protocols. But the use of GnRH instead of estradiol esters is being considered. Collectively, our group's data reinforce the need to customize approaches to estrous cycle control according to the genetic composition of bovine females.(AU)

Reproductive rates and performance traits in beef cattle infected by Bovine Herpesvirus / Índices reprodutivos e características de desempenho em bovinos decorte infectados pelo Herpevírus Bovino 1

Reproductive rates and performance traits in beef cattle females infected by Herpesvirus Bovine-1 (BoHV-1) were evaluated in a farm at São Paulo state, Brazil. Gir, Guzerá, Nelore and Caracu purebred animals were examinated to BoHV-1 (ELISA) at the beginning of the breeding season and the occurrence of reactors was 54.2% (386/712). BoHV-1 did not interfere in the pregnancy rates of both reagent 80.3% (310/386) and non-reagent - 74.5% (243/326) females. It did not reduce the parturition rate of both reagent - 97.7% (300/307) and non-reagent - 93.8% (225/240) females. Total rate of stillbirths in BoHV-1 reagent females - 1.3% (4/300) did not differ from non-reagent females - 2.2% (5/225). BoHV-1 did not affect performance traits for reagent and non-reagent females, respectivelly, to daily weight gain during the breeding season (459.90 ± 2.82g and 466.63 ± 2.87g), body condition score at the beginning of the breeding season (6.89 ± 0.08 and 6.99 ± 0.08), body condition score at the end of the breeding season (7.73 ± 0.06 and 7.71 ± 0.06), weight at parturition (419.17 ± 3.34kg and 425.97 ± 3.22kg). It was concluded that non-vaccinated beef cattle females infected by BoHV-1 and bred under adequate extensive management, with body condition scare over 5 and gain of weight during the breeding season presented good pregnancy, parturition and birth rates, no matter the breed, genetic group, age and seroconvertion. (AU)

Avaliou-se índices reprodutivos e características de desempenho em fêmeas bovinas de corte, infectadas pelo Herpesvírus Bovino-l (BoHV-1), em um rebanho no Estado de São Paulo, Brasil. Animais das raças Gir, Guzerá, Nelore e Caracu foram monitorados no início da estação de monta e a sororeatividade ao BoHV-1 pelo teste ELISA foi 54,2% (386/712). O BoHV-1 não interferiu no índice de prenhez de matrizes reagentes - 80,3% (310/386) e não reagentes - 74,5% (243/326) e nem reduziu a taxa de parição de matrizes reagentes - 97,7% (300/307) e não reagentes - 93,8% (225/240). O coeficiente de natimortalidade de matrizes reagentes ao BoHV-1 - 1,3% (4/300) não diferiu da encontrada para as não reagentes - 2,2% (5/225). O BoHV-1 não afetou a média de algumas características de desempenho de fêmeas reagentes e não reagentes, respectivamente, como ganho de peso médio diário durante a estação de monta (459,90 ± 2,82g e 466,63 ± 2,87g), condição corporal na entrada da estação de monta (6,89 ± 0,08 e 6,99 ± 0,08), condição corporal na saída da estação de monta (7,73 ± 0,06 e 7,71 ± 0,06) e peso à parição (419,17 ± 3,34kg e 425,97 ± 3,22kg). Concluiu-se que matrizes de corte infectadas pelo BoHV-1 e não vacinadas, criadas sob condições adequadas de manejo zootécnico extensivo e nutricional, como escore corporal acima de 5 e ganho de peso durante a estação de monta, apresentaram bons índices de prenhez, parição e natalidade, independente da raça, grupo genético, faixa etária e soroconversão.(AU)