Abstract The objective of this study was to evaluate the effect of different levels of concentrate supplementation on carcass characteristics of heifers finished on Tifton 85 pasture. Thirty-two cross-breed heifers (Charolais and Nellore) on average aged 25.51 months and weighing 298 kg were used in a completely randomized experiment. The animals were distributed uniformly to receive four different levels of concentrates based on the body weight: 0.0; 0.4; 0.8 and 1.2%. Animals were slaughtered at 29 months of age. There was increasing linear effect of levels energy supplementation on: slaughter weight, hot and cold carcass weights,hot and cold dressing percentage, thigh thickness, carcass compactness, and L* and b* color values. It was observed quadratic effect of levels of energy supplementation on the percentage of fat in the carcass. Different levels of energy supplementation did not modify the accumulation of vital organs and visceral fat or the sensory attributes of the meat. Higher levels of energy supplementation promote increases in carcass traits of heifers when finished on Tifton 85 pasture.

Abstract The aim was to identify the predominant variables in the differentiation of meat quality of cattle submitted to surgical castration, immunocastration, or non-castration and finished in a tropical pasture. Thirty-nine crossbred cattle were used and distributed in three treatments: i) surgical castration; ii) immunocastration; and iii) non-castration, with an initial mean age of 14.06±0.72 months and a mean weight of 284.10±31.40 kg. We used the principal component analysis to differentiate the qualitative meat characteristics between the treatments. Based on that analysis, we found that the first three principal components explained 71.44% of the total variation in the meat quality data, which ensures that the variation found is associated with the effect of the treatments. The characteristics correlated with the first three principal components and responsible for the discrimination between sexual conditions were subcutaneous fat thickness, instrumental meat color, cooking loss and shear force. These characteristics were similar among castrated animals, regardless of the methods. Therefore, immunological castration preserves the attributes of the meat and prevents possible damage to the physical and mental integrity of the animals. Finally, principal component analysis is an important methodology in the objective investigation of beef meat attributes.

Abstract The objective of this study was to evaluate the effect of live weight and body condition score, measured at different growth stages, on the rebreeding of first-calf heifers. A total of 120 Nellore and Charolais crossbred heifers born between 2004 and 2008 were assessed. Their average age was 26±1 months, they were all from the same herd, and they received the same management from birth. To conduct this study, pre- and postpartum measurements of first-calf heifers were taken. The data were submitted to analysis of variance, and the means were compared using Student’s t-test at a significance level of α=0.05. A higher live weight of the heifer at 24 months enabled early calving within the first calving season (r=-0.30). First-calf heifers that rebred had a higher live weight at weaning (361 kg vs. 333 kg) than those that did not, although their live weights at calving were similar (344 kg vs. 332 kg). The rebreeding of first-calf heifers that gave birth with the same body condition score as in the first calving was dependent on positive live weight gain until the end of the following breeding season, especially during the calving-weaning period.

Resumen El objetivo de este estudio fue evaluar el efecto del peso vivo y la puntuación de condición corporal, medido en diferentes fases de crecimiento, sobre la repetición de la cría en primíparas. Se evaluaron 120 novillas cruzadas Nellore con Charoles nacidas entre los años 2004 y 2008, con edad media de 26±1 meses siendo todas oriundas del mismo rebaño y que reciben idéntico manejo desde el nacimiento. Para la realización de este estudio se utilizaron de la base de datos a las mediciones de la primípara en el pre y post-partos. Los datos fueron sometidos al análisis de varianza y las medias comparadas a través del test “t” de Student, a α=0,05 de probabilidad. El mayor del peso vivo de la novilla a los 24 meses proporciona que el parto ocurra por adelantado dentro de la primera estación de parición (r=-0,30). Primíparas que repetían crea presentaron mayor peso vivo al destete (361 kg vs. 333 kg) de las que no repitieron crea, aunque hubiera peso vivo al parto semejante entre sí (344 kg vs. 332 kg). La repetición de la cría de primíparas que paren con la misma puntuación de condición corporal, en el primer parto, es dependiente de la ganancia de peso vivo positivo hasta el final de la estación de montaje siguiente, principalmente en el período parto-destete.

ABSTRACT The objective was to evaluate the influence of calving and postpartum characteristics, measured in different genetic predominance, on the postpartum rebreeding. Were evaluated 437 partum from cows that received feeding management consisting of a forage base of the native field and the mating season consisted of 90 days. The measurements were used from the data base (age of cow, genetic predominance, body weight, body condition score and date of calving) of the cows in the partum and postpartum period. The variables were submitted to analysis of multiple variances, multiple regression, correlation and cluster. Already the groups formed by cluster analysis were submitted to analysis of variance and F test and the means, compared by Student’s t-test, α=0.05 probability. The increase in the mean at 0.14 points in the body condition score at calving and the occurrence of calving 9 days earlier at the calving season gives the Charolais genetically predominant cows repeat calves. The Nellore genetic predominance when they calved with similar body condition score (2.32 points) and showed a negative body weight gain at weaning (-3.0 kg and -2.1 kg) showed different behaviors, where they did not repeat the offspring, when they calved and weaned with smaller body weight.

O objetivo deste estudo foi avaliar, por meio de meta-análise, a qualidade da carne de vacas de acordo com o genótipo, sistema de terminação e classe de idade ao abate. A partir de uma pesquisa na internet, foram identificados 15 artigos com informações relacionadas à qualidade da carne de vacas para abate. Os dados foram agrupados conforme o genótipo das vacas, sendo eles: definidos zebuínos ou continentais, cruzados zebuínos x britânicos ou zebuínos x continentais; conforme o sistema de terminação: confinamento ou pastagem; em relação à idade de abate, sendo ela: até 4 anos (jovem), de 4 a 8 anos (adulta) ou mais de 8 anos de idade (velha). A carne das vacas mestiças continentais foi mais macia que a dos demais genótipos, seja através do painel de avaliadores ou pelo Shear. A carne de vacas terminadas em confinamento demonstrou maior grau de marmorização em relação à carne das fêmeas terminadas em pastagem. A redução da idade de abate das vacas melhorou a coloração da carne. O genótipo das vacas afeta os aspectos organolépticos da carne enquanto o sistema de terminação e idade de abate afetam os aspectos sensoriais da carne.

The aim of this study was to evaluate, by meta-analysis, the quality of the meat of the cows according to genotype, termination system and age class slaughter. During an online research were identified 15 articles with information related to meat quality of slaughtered cows. The data were grouped according of the genotype of cows being: zebu or continental defined, crossed zebu x british or zebu x continental; according to termination system: feedlot or grassland; according to age of slaughter, where: up to 4 years old (young), 4-8 years old (adult) or more than 8 years old (old). The meat of the continental crossbred cows was softer than the other genotypes, both panel of evaluators and by Shear. The meat of cows finished in feedlot showed higher marbling degree in relation to meat of females finished on grassland. The reduction of the slaughter age of cows improved the meat color. The cow's genotype affects the organoleptic aspects of meat while the finished system and slaughter age affects the sensory aspects of meat.

Foi avaliado o desempenho de vacas Charolês (C) e Nelore (N), agrupadas em três classes de idade, jovens (3 e 4 anos), adultas (5 a 7 anos) e velhas (8 ou mais anos), desmamadas aos três (precoce) ou sete meses no outono (tradicional). O peso no outono das vacas desterneiradas aos três meses (T3) foi 45 kg superior ao das vacas com remoção do bezerro aos sete meses (T7). O estado corporal aos sete meses também foi melhor nas vacas do T3 (3,3 contra 2,1 pontos). Vacas do T3 apresentaram maior ganho de peso do parto ao final do período reprodutivo e apresentaram maiores porcentagem de cio (81 contra 51%) e prenhez (67,2 contra 37,3%) e menor intervalo do parto ao primeiro cio pós-parto (102 contra 114 dias) que vacas do T7. Vacas adultas apresentaram melhor estado corporal aos sete meses e tiveram melhor desempenho reprodutivo do que vacas velhas e jovens. A diferença na porcentagem de prenhez entre o T3 e T7 foi mais evidente nas vacas jovens (42,11 contra 12,5%) e velhas (51,72 contra 35,71%) que nas adultas (62,50 contra 53,33%). Vacas C foram mais pesadas que as N, ao parto, aos três e sete meses pós-parto e apresentaram melhor estado corporal aos sete meses. O efeito do desmame precoce no desempenho reprodutivo foi mais evidente nas vacas C. A porcentagem de fêmeas prenhes nas C foi de 80,60% para o T3 e 41,90% para o T7, já nas N as porcentagens foram de 45,50 e 30,00%, respectivamente, para o T3 e T7. Nas vacas C, a produção de leite e a amamentação apresentaram efeito inibidor, sobre a reprodução, mais marcante que nas vacas N.

The experiment evaluated the performance of Charolais (C) and Nellore (N) cows of three age classes, young (3 and 4 years), adult (5 to 7 years) and old (8 or more years), weaned at three (early weaning) or seven months in the fall (traditional weaning). The weight of the cows at the fall was 45 kg higher for the cows weaned at three months (T3) than for the cows weaned at seven months (T7). The body condition at seven months was also better for T3 cows (3.3 vs. 2.1 points). The T3 cows had higher weight gain from calving to the end of the reproductive period and showed higher percentage of estrus (81 vs. 51%), of pregnancy (67.2 vs. 37.3%) and shorter interval between calving and first estrus (102 vs. 114 days) than T7 cows. Adult cows displayed better body condition at seven months and showed higher reproductive performance than young and old cows. The difference in pregnancy rate between T3 and T7 was more evident in young cows (42.11 vs. 12.5%) and old cows (51.72 vs. 35.71%) than in adult cows (62.5 vs. 53.33%). The C cows were heavier then N cows, at calving, at three and seven months, and displayed better body condition at seven months. The effect of early weaning on reproductive performance was more evident for C cows. The pregnancy rate of C cows was 80.6% for the T3 and 41.9% for the T7, while for the N cows the percentages were 45.5 and 30.0%, respectively, for T3 and T7. For C cows, milk production and the calves (presence and suckling) showed a stronger suppression on reproduction, than for N cows.