This study aimed to assess the performance, carcass traits, and non-carcass components of feedlot finished Texel crossbred lambs from different residual feed intake classes (RFI). Forty-seven uncastrated male Texel crossbred lambs (¾ Texel + ¼ Pantaneira) tested here were 4-month-old with an initial weight of 29.9 ± 5.5 kg. The lambs were confined for 70 days for individual dry matter intake (DMI) and average daily gain (ADG) assessment. The diet containing corn silage was provided as roughage, while the concentrate consisted of corn grain, soybean meal, urea, and mineral mixture with a 40:60 roughage to concentrate ratio and 76.34% total digestible nutrients (TDN). After confinement for 70 days, the lambs were slaughtered to assess carcass traits and non-carcass components. Based on the RFI, lambs were divided into three classes according to the standard deviation (sd): Positive RFI (inefficient, 0.5 above the mean), Negative RFI (efficient, 0.5 below the mean), and Medium RFI (intermediate). Classes with Negative (efficient) and Positive RFI (inefficient) showed no differences in ADG (0.321 vs 0.306 kg; P > 0.05). Dry matter intake (g d-1), and percentage of body weight (BW) differed significantly between the RFI classes (P < 0.05). Compared to lambs in the inefficient class, those in the efficient class (Negative RFI) showed a 9% reduction in DMI and had the same ADG. The lambs in either Positive or Negative RFI classes showed no weight differences between non-carcass components (P > 0.05). The RFI classes showed no differences in shrunk body weight, hot carcass weight, hot dressing, and weight of commercial cuts (P > 0.05). They showed no differences in neck, shoulder + shank, loin, rack, flank steak, rack cap off, and leg weights (P > 0.05). Our results indicate that improvement in feed efficiency, as a function of the RFI index, does not compromise performance and carcass traits of Texel crossbred lambs.

The present work aimed at evaluating models that predict the proportion of bone, muscle, and fat in ewe lamb carcasses using in vivo data obtained from the 9 th to 11 th rib section and from the 12 th rib. A study population of 30 wooled ewe lambs, derived from Texel breed crosses, were fed with different concentrate levels (0%, 20%, 40%, 60%, and 80%) and slaughtered at a weight of 37.70 ± 10.23 kg. Carcass fat content (FC%) and muscle content (MC%) were estimated from models using the proportion of muscle and fat in the 9 th to 11 th rib section or in the 12th rib, with or without additional data regarding subcutaneous fat thickness (SFT mm) or carcass ribeye area (RA cm 2 ). Carcass bone content (BC%) was predicted based on the proportion of bones in the 9 th to 11 th rib section or in the 12 th rib. Modeling with in vivo data included fasting body weight (FBW), withers height (WH), and ultrasound measurements of SFT and RA. The FC% could be estimated from the carcass SFT and fat content in the 12 th rib. The MC% was more accurately predicted from the proportion of muscles in the 9 th to 11 th rib section and from carcass RA. The 9 th to 11 th rib section provided the most accurate data for the prediction of BC%. To determine FC% and MC% from in vivo inputs, the model must include FBW and WH. In vivo FBW measurements alone allow for the estimation of BC%. We recommend the use of 12 th rib composition for the accurate estimation of carcass fat content, and the use of the 9 th and 11 th rib section for the prediction of carcass muscle and bone content. Models using in vivo data for the prediction of fat, muscle, and bone in ewe lambs should incorporate FBW and WH. ResumoObjetivou-se ajustar e avaliar modelos para predição das proporções de ossos, músculos e gordura da carcaça de borregas a partir de medidas obtidas in vivo, na seção HH e 12ª costela. As 30 borregas lanadas, oriundas de cruzamentos com ovinos da raça Texel, foram confinadas, alimentadas com níveis crescentes de concentrado (20; 40; 60 e 80%) e abatidas com 37,70 ± 10,23 kg. Para estimativa da proporção de gordura (GC%) e músculo (MC%) na carcaça foram ajustados modelos com os percentuais de gordura e músculo da 9ª a 11ª costela (seção HH) ou da 12ª costela, acompanhados ou não da espessura de gordura (EGS mm) ou da área de olho de lombo da carcaça (AOL cm 2 ), respectivamente. A proporção de ossos da carcaça (OC%) foi predito pelo percentual de ossos na seção HH ou da 12ª costela. Para predição in vivo, foram ajustadas equações com peso corporal em jejum (PCJ), altura de cernelha (AC), EGS e AOL medidas por ultrassom. A GC% pode ser estimada pela EGS obtida na carcaça e o teor de gordura na 12ª costela. O MC% pode ser predito de forma mais acurada considerando o teor de músculo na seção HH e a AOL da carcaça. A seção HH foi o modelo mais acurado para predição da OC%. Para obtenção da GC% e MC% in vivo os modelos devem incluir PCJ e AC. O OC% in vivo pode ser estimado a partir do PCJ. Recomenda-se a utilização da composição física da 12ª...

RESUMO Objetivou-se avaliar a terminação de novilhos Nelore, castrados e não castrados, em confinamento recebendo dieta alto grão, por meio do consumo de nutrientes, desempenho produtivo e viabilidade econômica da dieta. Foram utilizados 180 animais da raça Nelore, distribuídos em dois tratamentos (castrados e não castrados), com 90 animais por tratamento, com peso médio inicial de 415,64kg, recebendo dieta alto grão, constituída de 85% de milho grão e 15% de núcleo mineral-proteico-energético. O período experimental foi de 63 dias, sendo 15 dias para adaptação as dietas e 48 dias de confinamento. Houve efeito significativo para os consumos de nutrientes (P<0,05), apresentando médias de consumos de matéria seca de 7,60 e 7,96kg para animais castrados e não castrados. Houve efeito para as variáveis de desempenho produtivo em função da classe sexual (castrado e não castrado). Os animais não castrados apresentaram maiores (P<0,05) peso de abate, ganho de peso, peso de carcaça quente, rendimento de carcaça e melhor conversão alimentar quando comparados aos animais castrados terminados em confinamento recebendo dieta alto grão. Os animais castrados apresentaram maior espessura de gordura que os animais não castrados, de 4,80 e 3,40mm, respectivamente. Os animais não castrados apresentaram margem de lucro/animal de R$ 256,00 e os castrados de R$ 202,80. Recomenda-se a terminação de novilhos Nelore em confinamento recebendo dieta alto grão. Os animais não castrados apresentaram maior ganho de peso e lucro no sistema de terminação em confinamento recebendo dieta alto grão.

874Predição da composição física e química da carcaça de borregas pela seção da 9ª a 11ª costelas ou 12ª costelaPrediction of physical and chemical composition carcass of ewe lambs by 9-11 th ribs section or 12 th rib

Due to the multifactorial aspect between the morphogenetic, morphological and agronomic characteristics of the forage plants, it is necessary to look for management options that increase the production and the utilization of the mass of forage submitted to different frequencies of defoliation and nitrogen levels. The objective of this study was to verify the effects of two defoliation frequencies and two levels of nitrogen applied in a single dose on the morphogenetic, structural and forage production of piatan grass in the water period. The work was carried out in the agrostological field of the Faculty of Veterinary Medicine and Animal Science (UFMS), Campo Grande -MS. The experimental area was composed of 12 plots of 18 m² each of Brachiaria brizantha cv. Piatã (Syn. Urochloa brizantha cv. Piatã). The experimental design was completely randomized and the treatments consisted of two defoliation frequencies (with cut intervals of 28 and 35 days) and single application of two levels of nitrogen (100 and 200 kg ha -1 of N, in the form of urea) . Therefore, piatan grass pastures can be managed with a single fertilization of 100 kg ha -1 of N, with height close to 30 cm, as the production of leaf blades is not compromised. The single application of high doses of N does not increase the number, but raises the individual weights of existing tillers without affecting the morphogenic and morphological characteristics of the forage canopy. For pastures of piatã grass established in soils of good fertility it is recommended as a management strategy to use 20 cm as minimum height of cut or grazing and frequency of with interval of 28 days and height of approximately 30 cm. In established pastures, in the water period, if it is desired to reduce the dose fractionation of N, it is recommended as a single application the dose of up to 100 kg of N ha -1 immediately after the first cut.