Residual feed intake and reproductive traits of growing Purunã bulls.

Residual feed intake (RFI) and its relationship with reproductive traits was evaluated in growing bulls. Fifty-two growing Purunã bulls (11 mo initial age) were fed ad libitum in individual feedlot pens for 112 d. The animals were ranked for RFI and assigned to 3 feed efficiency groups: efficient (low RFI), intermediate (medium RFI), and inefficient (high RFI). Initial and final BW and ADG did not differ ( > 0.10) among the efficiency groups and were mean values of 254.6 (SD 44), 373.0 (SD 62), and 1.06 kg (SD 0.25), respectively. Mean values of 7.12 ± 0.28, 7.78 ± 0.28, and 8.04 ± 0.28 kg/d for DMI and -0.38 ± 0.04, -0.02 ± 0.04, and 0.51 ± 0.04 kg of DM/d for RFI were observed in the efficient, intermediate, and inefficient groups, respectively. Crude protein and ME intake were strongly correlated ( = 0.74, < 0.001 for both variables) with RFI and were lower ( < 0.10) in the efficient group (13.6 ± 0.2 g DM/kg BW∙d and 0.252 ± 0.003 Mcal/kg BW∙d, respectively) and greater ( < 0.10) in the inefficient group (15.3 ± 0.2 g DM/kg BW∙d and 0.282 ± 0.003 Mcal/kg BW∙d, respectively). Testicular measures (width, length, volume, ultrasonogram pixel intensity, and scrotum perimeter) and serum testosterone were not correlated with RFI ( > 0.10) but showed moderate to strong correlations with initial BW ( ranged from 0.36 to 0.51, ≤ 0.01), final BW ( ranged from 0.36 to 0.64, ≤ 0.01), and ADG ( ranged from 0.29 to 0.53, < 0.05). All the reproductive traits (testicular measurements and concentrations of serum testosterone) showed similar values among the efficiency groups. During the growth phase, feed intake and protein and energy requirements were decreased in more efficient bulls in terms of RFI. However, both groups maintained similar BW and ADG. Regardless of their RFI classification, Purunã bulls had the same reproductive traits during the growth phase.

Produção de novilhos castrados ou não castrados terminados em confinamento em idade jovem ou superjovem / Production of steers or bulls finished in feedlot at a young age or young steers

Avaliaram-se o desempenho produtivo e o rendimento de cortes comercias da carcaça de animais castrados ou não castrados terminados em confinamento e abatidos em idade jovem ou superjovem, alimentados com uma dieta contendo 11,2% de proteína bruta e 3,07Mcal de energia digestível/kg de matéria seca, composta de 50% de volumoso e 50% de concentrado. A idade no início do confinamento dos animais superjovens e jovens foi de nove e 22 meses, respectivamente. Maior PF foi observado para os animais jovens não castrados. O GMD foi 31% superior em favor dos novilhos jovens em relação aos superjovens. O CMS foi 27% superior para os novilhos jovens sobre os superjovens, e os novilhos não castrados consumiram 9% mais kg de matéria seca quando comparados aos castrados. A diferença de peso da meia carcaça entre animais não castrados e castrados foi de 43% para os jovens e de 18% para os superjovens. Maior percentual do corte serrote foi observado nos novilhos jovens castrados. Novilhos jovens apresentaram maior ganho de peso médio diário, bem como novilhos jovens não castrados apresentaram maior peso final. Animais não castrados apresentaram maiores pesos de meia carcaça fria, percentual de dianteiro e porção comestível do dianteiro em relação aos castrados.(AU)

The productive performance and yield of commercial cuts of the carcass of non-castrate or castrated males feedlot finished and slaughtered at a young age or young steers, fed a diet containing 11.2% crude protein and 3.07 Mcal of digestible energy / kg of dry matter, composed of 50% roughage and 50% concentrate were evaluated. The initial age at the beginning of confinement of young steers and steers were 9 and 22 months, respectively. Greater FW was observed for young non-castrate. The ADG was 31% higher for the steers in relation to young steers. The DMI was 27% higher for steers than young steers and non-castrated consumed 9% more dry matter kg compared to the castrated. The half-carcass weight difference between non-castrated and castrated animals was 43% for steers and 18% for young steers. Higher percentage hacksaw cut was observed in castrated steers. Steers showed higher average daily weight gain, as well as non-castrate steers showed higher final weight. Non-castrate animals have higher half cold carcass weights, front percentage, and of edible portion of the front in relation to castrated.(AU)

Características de desempenho e eficiência alimentar de touros Purunã em crescimento de três classes de consumo alimentar residual / Performance and feed efficiency traits of Purunã growing bulls of three groups of residual feed intake

Objetivou-se avaliar as características de desempenho, consumo e eficiência alimentar de touros Purunã em crescimento de três classes de consumo alimentar residual (CAR): eficiente, intermediária e ineficiente. Foram avaliados 110 tourinhos com média de 10 meses de idade e 233kg de peso corporal (PC), distribuídos aleatoriamente em baias individuais em confinamento. A dieta, em base de matéria seca (MS), foi composta por 420g/kg de concentrado e 580g/kg de silagem de milho, e fornecida à vontade. O consumo de MS diário e o ganho médio diário (GMD) foram avaliados durante 112 dias. O PC inicial e final e o GMD foram semelhantes entre as classes de eficiência e apresentaram valores médios de 233kg, 360kg e 1,14kg/dia. Valores médios de 7,19; 7,62 e 8,10kg/dia para consumo de MS e -048; -0,01 e 0,48kg MS/dia para CAR foram observados nas classes eficiente, intermediária e ineficiente. A conversão alimentar (CA) e a eficiência alimentar bruta (EAB) foram semelhantes entre as classes eficiente e intermediária, e apresentaram média de 6,65kg MS/kg ganho e 153g ganho/kg MS. A classe ineficiente apresentou maior CA e menor EAB, com valores de 7,40kg MS/kg ganho e 138g ganho/kg MS. A eficiência parcial de crescimento (EPC) diferiu entre as classes de eficiência e apresentou valores médios de 294; 277 e 255g ganho/kg MS para crescimento nas classes eficiente, intermediária e ineficiente. O CAR apresentou correlação moderada a alta com CA, EAB e EPC, e a diminuição do CAR levou à redução da CA em 12,2%, e aumento da EAB e EPC em 13,3% e 15,5%. Tourinhos Purunã eficientes para CAR consomem menos alimento, mas mantêm o mesmo nível de produção que os ineficientes. Assim, a classificação com base no CAR permite a identificação de animais com potencial para melhorar a eficiência produtiva do rebanho.

This trial aimed to evaluate the performance, feed intake and feed efficiency traits of Purunã growing bulls of three groups of residual feed intake (RFI): efficient, intermediary and inefficient. There were used 110 growing bulls with average of 10 months of age and 233kg of body weight (BW) which were randomly allocated in individual feedlot pens. The diet was composed, in dry matter (DM) basis, by 420g/kg of concentrate and 580g/kg of corn silage, and was offered ad libitum. Daily dry matter intake (DMI) and average daily gain (ADG) were assessed during 112 days. Initial and final BW and ADG not differed between the efficiency groups and showed mean values of 233kg, 360kg and 1.14kg/d. Mean values of 7.19, 7.62 and 8.10kg/d to DMI and -0.48, -0.01 and 0.48kg DM/d to RFI were observed in efficient, intermediary and inefficient groups. Feed conversion ratio (FCR) and gross feed efficiency (GFE) not differed between efficient and intermediary groups, which showed means of 6.65kg DM/kg gain and 153g gain/kg DM. Inefficient group showed higher FCR and lower GFE, with mean values of 7.40kg DM/kg gain and 138g gain/kg DM. Partial efficiency of growth (PEG) differed between the efficiency groups and showed means of 294, 277 and 255g gain/kg DM for growth in efficient, intermediary and inefficient groups. RFI showed moderate to high correlations with FCR, GFE and PEG, and decrease of RFI resulted in decrease of FCR in 12.2%, increase of GFE in 13.3% and increase of PEG in 15.5%. Efficient Purunã growing bulls (low RFI) present lower feed intake, but maintains the same production level that inefficient ones (high RFI). Thus, RFI classification allows identifying animals with potential to improve the productive efficiency of herd.