Strategies of virginiamycin supplementation in the postweaning phase on growth performance and carcass quality of beef cattle.

The present study evaluated the effects of supplementing VM in grazing cattle during the rearing phase on performance and carcass quality of beef cattle in the finishing phase. Two experiments with a randomized block design were conducted in consecutive years to contrast two post-weaning supplementation strategies using VM at 45 mg/100 kg body weight (BW). In the first year, treatments were protein supplement in the dry season and mineral supplement in the rainy season versus the addition of VM both in the protein and mineral supplements. In the second year, was contrasted with protein supplement in the dry season and protein-energy supplement in the rainy season. Performance, carcass traits, and carcass quality were evaluated at the end of both phases. In Year 1, adding VM in mineral supplement increased final backfat thickness (P=0.05), backfat gain (P=0.06), final rump fat thickness (P=0.02), and rump fat gain (P=0.01). In the finishing phase, VM-treated cattle had a greater dry matter intake (P=0.03) and tended to show a greater backfat thickness than non-treated cattle (P=0.07). In Year 2, no VM effects were observed on post-weaning phase performance and carcass traits. However, cattle-fed VM during the post-weaning phase tended to show a lower feed conversion ratio (P=0.09) and had a significantly higher gross feed efficiency (P=0.03) than non-treated cattle at slaughter. Virginiamycin supplementation during rearing on pasture improves performance and carcass fattening in the growth phase and has a residual effect in the finishing phase that may reflect greater backfat thickness and gross feed efficiency.

Alternative methodologies for genotyping polymorphisms in the CAST and CAPN1 genes in beef cattle

The objectives of this study were to genotype single nucleotide polymorphisms (SNP) AF159246:g.2959A>G (CAST/DdeI) and AF248054.2:g.6545C>T (CAPN4751) in beef cattle by PCR-RFLP (Polymerase Chain Reaction - Restriction Fragment Length Polymorphism), using the restriction enzyme DdeI for both SNP, and describe the use of these genotyping methodologies for the first time. For the SNP located in the CAST gene, new primers were designed, and for the SNP of the CAPN1 gene, the same primers previously described in the literature were used. Bonsmara, Caracu, Senepol, Nelore, and Angus bulls were chosen from among the most used bulls in breeding programs according to their genealogy and the lowest possible degree of parentage between them to ensure an experimental sample representative of the genetic variability in each breed. For the CAST and CAPN1 genes, respectively, the following number of animals were analyzed: Bonsmara (n = 25/22), Caracu (n = 25/26), Senepol (n = 25/24), Nelore (n = 26/26), and Angus (n = 25/24). The accuracy of these methodologies was confirmed by direct sequencing of PCR products generated for the two polymorphisms. The new primers developed for CAST/DdeI SNP detection and the use of DdeI enzyme for CAPN4751 SNP detection were effective in genotyping, since no inconclusive genotypes were observed for these genes. Thus, the genotyping of beef cattle using the PCR-RFLP technique for CAST and CAPN1 genes is robust, relatively inexpensive, and easy to perform in any basic molecular biology laboratory. If the association of these markers with traits of economic interest in beef cattle is confirmed in new studies, these methodologies may contribute to the selection of animals with superior genetics, i.e., with the potential to produce better-quality meat, either by marker-assisted selection or by the inclusion of these polymorphisms in high-density marker panels.(AU)

Parametrization of the Davis Growth Model using data of crossbred Zebu cattle

The system of differential equations proposed by Oltjen et al. [1986, named Davis Growth Model (DGM)] to represent cattle growth has been parameterized with data from Bos taurus (British) and Bos indicus (Nellore) breeds. The DGM has been successfully used for simulation and decision support in the United States. However, the effect of about 30 years of genetic improvement and the use of different breeds may affect the model parameter values, which also may need to be re-estimated for crossbred animals. The aim of this study was to estimate parameter values and confidence intervals for the DGM with growth and body composition data from Zebu crossbred animals. Confidence intervals and asymptotic distribution were generated through nonparametric bootstrap with data from a field experiment conducted in Brazil. The parameters showed normal probability distribution for most scenarios. The rate constant for deoxyribonucleic acid (DNA) synthesis had a minimum increase of 156 % and the maximum of 389 %, compared to the original values and the maintenance requirement had a minimum increase of 126 % and maximum of 160 % compared to the original values. Lower limits of 95 % confidence intervals for the parameters related to maintenance and protein accretion rates were higher than the original estimates of the DGM, evidencing genetic differences of the Zebu crossbred animals in relation to the original DGM parameters.

Parametrization of the Davis Growth Model using data of crossbred Zebu cattle

The system of differential equations proposed by Oltjen et al. [1986, named Davis Growth Model (DGM)] to represent cattle growth has been parameterized with data from Bos taurus (British) and Bos indicus (Nellore) breeds. The DGM has been successfully used for simulation and decision support in the United States. However, the effect of about 30 years of genetic improvement and the use of different breeds may affect the model parameter values, which also may need to be re-estimated for crossbred animals. The aim of this study was to estimate parameter values and confidence intervals for the DGM with growth and body composition data from Zebu crossbred animals. Confidence intervals and asymptotic distribution were generated through nonparametric bootstrap with data from a field experiment conducted in Brazil. The parameters showed normal probability distribution for most scenarios. The rate constant for deoxyribonucleic acid (DNA) synthesis had a minimum increase of 156 % and the maximum of 389 %, compared to the original values and the maintenance requirement had a minimum increase of 126 % and maximum of 160 % compared to the original values. Lower limits of 95 % confidence intervals for the parameters related to maintenance and protein accretion rates were higher than the original estimates of the DGM, evidencing genetic differences of the Zebu crossbred animals in relation to the original DGM parameters.(AU)

Eficiência alimentar e qualidade da carne de novilhas de corte cruzadas classificadas através do consumo alimentar residual / Feed efficiency and meat quality of crossbred beef heifers classified according to residual feed intake

This study aimed to evaluate feed efficiency and meat quality of 31 three-crossbred beef heifers during 84 days in a feedlot system. A 60:40 concentrate and sorghum silage ration on DM basis (ME = 2.73Mcal/kg of DM, CP = 11.90% DM) was fed ad libitum. Based on residual feed intake (RFI) calculations, the heifers were ranked in three groups of feed efficiency: High RFI (average mean = 0.776; n = 9), medium RFI (average mean = -0.010; n = 11), and low RFI (average mean = - 0.624; n = 11). High RFI heifers consumed 4.56% more DM per day than low RFI heifers (P <0.05). The ADG did not differ (P> 0.05) among RFI groups (1.40kg/day). No differences (P>0.05) were detected for digestibility of the nutrients: DM (64.00%), CP (60.01%), crude fat (72.90%), NDF (54.80%) and non-fibrous carbohydrate (NFC) (78.91%). There were no differences between low and high RFI groups for slaughter weight (475.00 vs. 479.55kg), hot carcass weight (259.09 vs. 261.44kg), Longissimus dorsi (LD) area (69.02 vs. 68.11 cm2), back-fat thickness (5.74 vs. 6.26 cm), shear force (5.45 vs. 5.19kg), sensorial traits of LD muscle, LD color (intensities L=40.47 a*=24.74 and b*=16.13) or commercial cuts yield. Low RFI heifers presented similar meat quality and carcass traits as high RFI heifers, however low RFI heifers consumed less DM (kg/d).(AU)

O objetivo com este estudo foi avaliar a eficiência alimentar, qualidade da carne e digestibilidade dos nutrientes em 31 novilhas de corte mestiças durante 84 dias de confinamento. A relação volumoso:concentrado da dieta oferecidaad libitum foi de 60:40 (EM= 2,73 Mcal/kg MS, PB= 11,90% MS). Baseado no consumo alimentar residual (CAR), os animais foram classificados em três grupos de eficiência alimentar: Alto CAR (média= 0,776; n = 9), médio CAR (média= -0,010; n = 11) e baixo CAR (média = - 0,624; n = 11). Novilhas alto CAR consumiram 4,56% a mais de MS diária comparadas à novilhas baixo CAR (P<0,05). O ganho médio diário não diferiu (P>0,05) entre animais de diferentes grupos de eficiência (1,40kg/dia). Não houveram diferenças para a digestibilidade dos nutrientes entre os grupos avaliados: MS (64,00%), PB (60,01%), EE (72,90%), FDN (54,80%) e CNF (78,91%). Não houveram diferenças entre alto e baixo CAR para peso ao abate (475,00 vs. 479,55kg), peso de carcaça quente (259,09 vs. 261,44kg), área do músculo Longissimus dorsi(LD) (69,02 vs. 68,11 cm2), espessura de gordura subcutânea (5,74 vs. 6,26cm), maciez (5,45 vs. 5,19kg), características sensoriais do músculo LD, coloração do músculo LD (intensidades L=40,47 a*=24,74 e b*=16,13) ou rendimento de cortes comerciais. Novilhas baixo CAR apresentaram similar qualidade de carcaça e carne à novilhas classificadas como alto CAR, entretanto novilhas baixo CAR apresentaram um menor consumo de MS (kg/d).(AU)

Eficiência alimentar e qualidade da carne de novilhas de corte cruzadas classificadas através do consumo alimentar residual / Feed efficiency and meat quality of crossbred beef heifers classified according to residual feed intake

This study aimed to evaluate feed efficiency and meat quality of 31 three-crossbred beef heifers during 84 days in a feedlot system. A 60:40 concentrate and sorghum silage ration on DM basis (ME = 2.73Mcal/kg of DM, CP = 11.90% DM) was fed ad libitum. Based on residual feed intake (RFI) calculations, the heifers were ranked in three groups of feed efficiency: High RFI (average mean = 0.776; n = 9), medium RFI (average mean = -0.010; n = 11), and low RFI (average mean = - 0.624; n = 11). High RFI heifers consumed 4.56% more DM per day than low RFI heifers (P 0.05) among RFI groups (1.40kg/day). No differences (P>0.05) were detected for digestibility of the nutrients: DM (64.00%), CP (60.01%), crude fat (72.90%), NDF (54.80%) and non-fibrous carbohydrate (NFC) (78.91%). There were no differences between low and high RFI groups for slaughter weight (475.00 vs. 479.55kg), hot carcass weight (259.09 vs. 261.44kg), Longissimus dorsi (LD) area (69.02 vs. 68.11 cm2), back-fat thickness (5.74 vs. 6.26 cm), shear force (5.45 vs. 5.19kg), sensorial traits of LD muscle, LD color (intensities L=40.47 a*=24.74 and b*=16.13) or commercial cuts yield. Low RFI heifers presented similar meat quality and carcass traits as high RFI heifers, however low RFI heifers consumed less DM (kg/d).

O objetivo com este estudo foi avaliar a eficiência alimentar, qualidade da carne e digestibilidade dos nutrientes em 31 novilhas de corte mestiças durante 84 dias de confinamento. A relação volumoso:concentrado da dieta oferecidaad libitum foi de 60:40 (EM= 2,73 Mcal/kg MS, PB= 11,90% MS). Baseado no consumo alimentar residual (CAR), os animais foram classificados em três grupos de eficiência alimentar: Alto CAR (média= 0,776; n = 9), médio CAR (média= -0,010; n = 11) e baixo CAR (média = - 0,624; n = 11). Novilhas alto CAR consumiram 4,56% a mais de MS diária comparadas à novilhas baixo CAR (P0,05) entre animais de diferentes grupos de eficiência (1,40kg/dia). Não houveram diferenças para a digestibilidade dos nutrientes entre os grupos avaliados: MS (64,00%), PB (60,01%), EE (72,90%), FDN (54,80%) e CNF (78,91%). Não houveram diferenças entre alto e baixo CAR para peso ao abate (475,00 vs. 479,55kg), peso de carcaça quente (259,09 vs. 261,44kg), área do músculo Longissimus dorsi(LD) (69,02 vs. 68,11 cm2), espessura de gordura subcutânea (5,74 vs. 6,26cm), maciez (5,45 vs. 5,19kg), características sensoriais do músculo LD, coloração do músculo LD (intensidades L=40,47 a*=24,74 e b*=16,13) ou rendimento de cortes comerciais. Novilhas baixo CAR apresentaram similar qualidade de carcaça e carne à novilhas classificadas como alto CAR, entretanto novilhas baixo CAR apresentaram um menor consumo de MS (kg/d).

Caracterização do haplótipo mitocondrial de uma amostra de touros da raça nelore, representativa das principais linhagens comercializadas no Brasil / Mitochondrial haplotype characterization of one sample of Nellore bulls representing the main lines marketed in Brazil

Os bovinos podem ser classificados em dois grandes grupos de acordo com sua origem e distribuição geográfica: o grupo Bos taurus, representado pelos bovinos europeus, e o Bos indicus ou zebuíno, que vive nas regiões tropicais. O rebanho brasileiro é constituído principalmente por raças zebuínas, das quais predomina a raça Nelore. Os mamíferos possuem, além do genoma nuclear, um genoma citoplasmático encontrado nas mitocôndrias, o DNA mitocondrial (mtDNA), que apresenta herança exclusivamente materna. Há relatos que os polimorfismos no mtDNA podem afetar a adaptação das raças bovinas a condições ambientais distintas bem como a produção animal. Provavelmente a maioria da população brasileira de animais da raça Nelore foi obtida por retrocruzamentos de vacas nativas com touros zebuínos e, portanto, abrigam mtDNA de origem Bos taurus. O objetivo deste estudo foi caracterizar o haplótipo do mtDNA de uma amostra de touros cujas genealogias são representativas das principais linhagens da raça Nelore. A investigação do haplótipo do mtDNA (Bos taurus ou Bos indicus) foi realizada por meio de PCR alelo-específica para amplificação de uma região 366 pb do gene rRNA 16S de mtDNA, no qual um polimorfismo diferencia mtDNA Bos taurus e Bos indicus. Observou-se, nesta amostragem, 76,66% dos animais com mtDNA de origem Bos taurus. Estes resultados reforçam a hipótese de que a formação da raça Nelore no Brasil provavelmente resultou do cruzamento absorvente de touros Bos indicus com matrizes Bos taurus.

The cattle can be classified into two groups according to their origin and geographic distribution: Bos taurus, represented by the European cattle, and Bos indicus, originated in Asia. The Brazilian herd consists mainly of Zebu catlle, mainly consisted of Nellore breed animals. Mammals have in addition to the nuclear genome, a cytoplasmic genome found in mitochondria, the mitochondrial DNA (mtDNA), which shows exclusively maternal inheritance. There are reports that polymorphisms in mtDNA can affect the adaptation of breeds to different environmental conditions and the animal production. Probably the majority of the Brazilian population of Nellore cattle was obtained by backcrossing of native cows with Zebu bulls and therefore harbors mtDNA of Bos taurus origin. The aim of this study was to characterize the mtDNA haplotype in a sample of bulls whose pedigrees are representative of the main lines of Nellore. The investigation of mtDNA haplotype (Bos taurus and Bos indicus) was performed by allele-specific PCR to amplify a 366 bp region of 16S rRNA gene of mtDNA, in which a mtDNA polymorphism differentiates Bos taurus from Bos indicus. In this sample, 76.66% of all animals presented mtDNA of Bos taurus origin. These results support the hypothesis that the stablishment of Nellore breed in Brazil probably resulted from backcrossing of Bos indicus bulls to Bos taurus females.

Caracterização do haplótipo mitocondrial de uma amostra de touros da raça nelore, representativa das principais linhagens comercializadas no Brasil / Mitochondrial haplotype characterization of one sample of Nellore bulls representing the main lines marketed in Brazil

Os bovinos podem ser classificados em dois grandes grupos de acordo com sua origem e distribuição geográfica: o grupo Bos taurus, representado pelos bovinos europeus, e o Bos indicus ou zebuíno, que vive nas regiões tropicais. O rebanho brasileiro é constituído principalmente por raças zebuínas, das quais predomina a raça Nelore. Os mamíferos possuem, além do genoma nuclear, um genoma citoplasmático encontrado nas mitocôndrias, o DNA mitocondrial (mtDNA), que apresenta herança exclusivamente materna. Há relatos que os polimorfismos no mtDNA podem afetar a adaptação das raças bovinas a condições ambientais distintas bem como a produção animal. Provavelmente a maioria da população brasileira de animais da raça Nelore foi obtida por retrocruzamentos de vacas nativas com touros zebuínos e, portanto, abrigam mtDNA de origem Bos taurus. O objetivo deste estudo foi caracterizar o haplótipo do mtDNA de uma amostra de touros cujas genealogias são representativas das principais linhagens da raça Nelore. A investigação do haplótipo do mtDNA (Bos taurus ou Bos indicus) foi realizada por meio de PCR alelo-específica para amplificação de uma região 366 pb do gene rRNA 16S de mtDNA, no qual um polimorfismo diferencia mtDNA Bos taurus e Bos indicus. Observou-se, nesta amostragem, 76,66% dos animais com mtDNA de origem Bos taurus. Estes resultados reforçam a hipótese de que a formação da raça Nelore no Brasil provavelmente resultou do cruzamento absorvente de touros Bos indicus com matrizes Bos taurus.(AU)

The cattle can be classified into two groups according to their origin and geographic distribution: Bos taurus, represented by the European cattle, and Bos indicus, originated in Asia. The Brazilian herd consists mainly of Zebu catlle, mainly consisted of Nellore breed animals. Mammals have in addition to the nuclear genome, a cytoplasmic genome found in mitochondria, the mitochondrial DNA (mtDNA), which shows exclusively maternal inheritance. There are reports that polymorphisms in mtDNA can affect the adaptation of breeds to different environmental conditions and the animal production. Probably the majority of the Brazilian population of Nellore cattle was obtained by backcrossing of native cows with Zebu bulls and therefore harbors mtDNA of Bos taurus origin. The aim of this study was to characterize the mtDNA haplotype in a sample of bulls whose pedigrees are representative of the main lines of Nellore. The investigation of mtDNA haplotype (Bos taurus and Bos indicus) was performed by allele-specific PCR to amplify a 366 bp region of 16S rRNA gene of mtDNA, in which a mtDNA polymorphism differentiates Bos taurus from Bos indicus. In this sample, 76.66% of all animals presented mtDNA of Bos taurus origin. These results support the hypothesis that the stablishment of Nellore breed in Brazil probably resulted from backcrossing of Bos indicus bulls to Bos taurus females.(AU)