RESUMO -Neste experimento, avaliou-se o efeito de sexo (macho e fêmea) e de quatro distintos pesos de abate (28, 32, 36, e 40 kg) sobre a morfometria da carcaça, os pesos dos cortes, a composição tecidual e os componentes não constituintes da carcaça, em cordeiros mestiços Ile de France x Corriedale, terminados em confinamento. Utilizaram-se 40 animais (20 machos e 20 fêmeas), desmamados aos 60 dias e alimentados, à vontade, com uma ração com 16,46% de PB e 67,63% de NDT. Foram divididos em quatro grupos de machos (G1M, G2M, G3M e G4M), sacrificados, respectivamente, com os pesos supracitados, e, da mesma forma, quatro grupos de fêmeas (G1F, G2F, G3F e G4F). Determinaram-se as medidas da carcaça e, de forma subjetiva, a condição corporal, o grau de conformação e o grau de gordura de cobertura. Calcularam-se os índices de compacidade da carcaça e da perna. Foram registrados os pesos e as porcentagens de sete cortes da meia carcaça, bem como as porcentagens de osso, músculo e tecido adiposo, avaliadas por meio de dissecção do lombo. A espessura da gordura de cobertura foi determinada na região lombar. O estudo morfométrico confirmou maior alongamento ósseo dos machos. De maneira geral, as carcaças apresentaram-se com bom acabamento, segundo os índices de compacidade verificados. Os cortes das carcaças das fêmeas foram mais pesados que os dos machos (exceto para o peso de 28 kg ao abate), principalmente em função dos maiores teores de gordura. Destaca-se a representabilidade dos pesos da pele e do conteúdo gastrintestinal na determinação do rendimento da carcaça. Pelos resultados obtidos, recomenda-se 28 kg como peso referência para sacrifício.Palavras-chave: carne de cordeiro, carcaça ovina, ovino, produção de cordeiro Sex and Slaughter Weight Effects on Meat Production of Lambs. Carcass Morphometric Evaluation, Cuts Weights, Tissues and Offals PercentagesABSTRACT -This experiment was carried out to evaluate the effects of sex (males x females) and four slaughter weights (28, 32, 36 and 40 kg), on carcass morphometry, cuts weights, tissues and offals percentages, from crossbred lambs Ile de France x Corriedale, finished in feedlot. Fourty lambs (20 males and 20 females), were weaned at 60 days of age and were full fed a diet with 16.46% CP and 67.63% TDN. They were divided in 4 male groups (G1M, G2M, G3M and G4M), slaughtered respectively with the mentioned weights, and, in the same way, 4 female groups (G1F, G2F, G3F and G4F). It was determined the carcass measures, body score, carcass conformation and fat grades; carcass and leg compacity index; the weights and porcentages of 7 cuts from the half carcass; muscle, bone and fat tissue percentages from the loin and fat thickness on the loin. The morfometric study showed a higher osseous elongation in the males carcasses. Generally, the compacity index indicated a good carcass finishing. The female carcass cuts were heavier than the male cuts (except for the live weight of 28 kg), ascribed to the higher fat content. Among the offals, skin and gastrointestinal conten...

Please cite this article in press as: Bozicovich, T.F.M., et al., Effect of environmental enrichment and composition of the social group on the behavior, welfare, and relative brain weight of growing rabbits. Appl. Anim. Behav. Sci. (2016), http://dx. a b s t r a c tThe objective of the study was to investigate if environmental enrichment and the composition of the social group would affect the behavior and relative brain weight of growing rabbits. Rabbits (72 males and 72 females) were assigned to cages with or without enrichment and one of three social groups (males, females, or mixed-gender). Two eucalyptus sticks suspended from the cage ceiling were provided in the enriched cages based on the results of a preliminary trial conducted on growing rabbits (n = 48) showing that pieces of wood (Eucalyptus sp, Pinus sp) or bamboo (Dendrocalamus giganteus) were preferred over PVC pipe (P < 0.05). Rabbits were exposed to the experimental conditions between six and 11 weeks of age. Behavioral activities were video recorded for 24 h, at 7, 10 and 11 weeks of age. Growth performance was recorded from 42 to 77 days of age, whereas skin wounds and brain weight were recorded at 77 days. At 70 days of age, rabbits in non-enriched cages showed a higher proportion of self-grooming (P = 0.012) than those in enriched cages. Enrichment decreased the number of social interactions among rabbits (P = 0.012), but increased aggressive behavior (P = 0.007). The number of animals showing skin wounds on day 77 was lower (P = 0.006) in enriched than in non-enriched cages. The incidence of social interactions was higher (P < 0.05) and of stereotypes was lower (P < 0.05) in mixed-gender groups than in same-sex groups. Female groups showed the lowest incidence of aggressive behavior (P < 0.05). The number of individuals with skin injuries was higher in mixed-gender groups (P < 0.05) than in female groups; male groups were intermediate. Growth performance was unaffected by enrichment or by the composition of social group. Males in enriched cages had heavier brains (P < 0.05) than those in nonenriched cages. Although aggressive behaviors were more frequent, the number of skin wounds on day 77 was lower in rabbits from enriched cages, suggesting improved welfare. Based on the increased frequency of social interactions and decreased incidence of stereotyped behavior, mixed-gender groups should be housed in collective cages from weaning up to 11 weeks of age. However, if the incidence of skin wounds is considered, only females can be housed in same-sex groups. For males, individual cages should be preferred. Whether environmental enrichment induces morphologic changes in male rabbits' brains should be further investigated.

RESUMO -Realizou-se o presente estudo com o objetivo de avaliar o efeito de sexo (machos inteiros x fêmeas) e de quatro pesos ao abate (28, 32, 36 e 40 kg) sobre o desempenho, os caracteres da carcaça e resultados econômicos de cordeiros mestiços ½ Ile de France x ½ Corriedale, terminados em sistema de confinamento. Quarenta animais (20 machos e 20 fêmeas) foram desmamados aos 60 dias e alimentados à vontade com uma ração contendo 16,46% de PB e 67,63% de NDT. Foram divididos em quatro grupos de machos (G1M, G2M, G3M e G4M) e quatro grupos de fêmeas (G1F, G2F, G3F, e G4F), sacrificados, respectivamente, com os pesos supra citados. Determinaram-se o ganho médio de peso diário (GMPD), o peso do corpo vazio (PCV), os pesos de carcaça quente (PCQ) e fria (PCF), as perdas ao resfriamento (PR), os rendimentos comercial (RC) e verdadeiro (RV) e o pH da carne em três momentos. Observou-se efeito de sexo para GMPD, com superioridade dos machos. Houve efeito de peso ao abate sobre PCQ e PCF e também de sexo, tendo as fêmeas superado os machos em G3 e G4, para PCQ, e em G2, G3 E G4, para PCF. Constataram-se maiores valores de RC e RV para as fêmeas, em G3 e G4. Todos os grupos apresentaram-se similares em relação ao pH da carne, o qual descreveu uma curva dentro dos padrões esperados. O estudo econômico destacou G1M como tendo apresentado melhor conversão alimentar e maior renda líquida/animal. Entre as fêmeas, G1F foi o melhor, destacando-se as rendas líquidas negativas constatadas em G3F e G4F. Concluiu-se que o melhor peso ao abate foi 28 kg, tanto para os machos, como para as fêmeas. No caso dos machos, tolerar-se-ia o peso de 32 kg, apesar de ter propiciado renda líquida 12,8% inferior a G1M.Palavras-chave: carne de cordeiro, carcaça ovina, ovino, produção de cordeiro Effects of Sex and Slaughter Weight on Meat Production of Lambs. I. Growth Rate, Carcass Quantitative Traits, Meat pH and Economic ResultsABSTRACT -This experiment was carried out to evaluate the effects of sex(males x females) and four slaughter weights (28, 32, 36 and 40 kg) on the perfomance, carcass traits and economic results from crossbred lambs, finished in feedlot. Fourty ½ Ile de France x ½ Corriedale lambs (20 males and 20 females), were weaned at 60 days of age and were full fed a diet with 16.46% CP and 67.63% TDN. They were divided in four male groups (G1M, G2M, G3M and G4M), slaughtered respectively with the mentioned weights; and, in the same way, four female groups (G1F, G2F, G3F and G4F). There was sex effect on average daily weight gain, with advantage of the males. There was slaughter weigth and sex effects on hot carcass weight and cool carcass weight; the females surpassed the males in G3 and G4 for cool carcass weight. The commercial and biological yields were higher for the females from G3 and G4. All the groups were similar for meat pH, which described a standard curve. The economic evaluation showed that G1M had the best net income. Among the female groups, G1F was the best, detaching negative net incomes for G3F and G4F.

Rabbits are very sensitive to heat stress because they have difficulty eliminating excess body heat. The objective of the current study was to evaluate the effects of heat stress on slaughter weight, dressing percentage and carcass and meat quality traits of rabbits from two genetic groups. Ninety-six weaned rabbits were used: half were from the Botucatu genetic group and half were crossbreds between New Zealand White sires and Botucatu does. They were assigned to a completely randomized design in a 2 3 3 factorial arrangement (two genetic groups and three ambient temperatures: 188C, 258C and 308C) and kept under controlled conditions in three environmental chambers from 5 to 10 weeks of age. Slaughter took place at 10 weeks, on 2 consecutive days. Meat quality measurements were made in the longissimus muscle. Actual average ambient temperature and relative humidity in the three chambers were 18.48C and 63.9%, 24.48C and 80.2% and 29.68C and 75.9%, respectively. Purebred rabbits were heavier at slaughter and had heavier commercial and reference carcasses than crossbreds at 308C; however, no differences between genetic groups for these traits were found at lower temperatures. No genetic group 3 ambient temperature interaction was detected for any other carcass or meat quality traits. The percentages of distal parts of legs, skin and carcass forepart were higher in crossbred rabbits, indicating a lower degree of maturity at slaughter in this group. The percentage of thoracic viscera was higher in the purebreds. Lightness of the longissimus muscle was higher in the purebreds, whereas redness was higher in the crossbreds. Slaughter, commercial and reference carcass weights and the percentages of thoracic viscera, liver and kidneys were negatively related with ambient temperature. Commercial and reference carcass yields, and the percentage of distal parts of legs, on the other hand, had a positive linear relationship with ambient temperature. Meat redness and yellowness diminished as ambient temperature increased, whereas cooking loss was linearly elevated with ambient temperature. Meat color traits revealed paler meat in the purebreds, but no differences in instrumental texture properties and water-holding capacity between genetic groups. Purebred rabbits were less susceptible to heat stress than the crossbreds. Heat stress resulted in lower slaughter and carcass weights and proportional reductions of organ weights, which contributed to a higher carcass yield. Moreover, it exerted a small, but negative, effect on meat quality traits.

The objective of this study was to evaluate the effects of the interaction between genetic group (Botucatu or crossbred) and ambient temperature (thermoneutral, moderate or intense heat stress) on physiological indicators and performance of growing rabbits. Ninety-six weaned rabbits were used, half from the Botucatu genetic group and half crossbreds (New Zealand White males× Botucatu females). They were assigned to a completely randomized design in a 2× 3 factorial arrangement (two genetic groups and three ambient temperatures) with repeated measures (weeks). Colonic temperature, skin surface temperature, ear surface temperature, and respiratory rate were recorded from 42 to 67 days of age, whereas body weight and feed intake were recorded from 35 to 70 days of age. Average ambient temperature and relative humidity in the environmental chambers were 18.4°C and 63.9% (thermoneutral), 24.4°C and 80.2% (moderate heat stress) and 29.6°C and 75.9% (intense heat stress). Mean colonic temperatures ranged from 39.4 to 39.7°C across treatments. Botucatu rabbits showed higher (Pb 0.05) skin surface temperature under moderate heat stress than the crossbreds (33.0±0.1 vs. 32.6±0.1°C, respectively) and higher (Pb 0.01) respiratory rates independently of ambient temperature (161.4±2.8 vs. 148.1±2.8 breaths/min, respectively) than the crossbreds. Skin surface temperature, ear surface temperature and respiratory rate were positively related to ambient temperature. Under intense heat, average daily gain of Botucatu rabbits was higher (Pb 0.05) than that of the crossbreds (33.72±0.90 vs. 30.66±0.96 g/day, respectively), but there was no difference with thermoneutral or moderate heat conditions. This finding characterizes a genotype× environment interaction. When the age effect was considered, an increase in colonic temperature under intense heat was detected over the last week. Respiratory rate increased in both genetic groups from six to eight weeks of age, but the increase was more pronounced in Botucatu rabbits than in crossbreds, and the difference between groups was consistently amplified over weeks. Intense heat severely depressed average daily gain as age advanced, especially beyond week eight. As expected, feed consumption increased during the experimental period, but the rate was inversely proportional to ambient temperature. Under intense heat stress, feed consumption of Botucatu rabbits was slightly, but consistently, higher than that of the crossbreds as age advanced. Relevant differences in physiological responses and growth performance between rabbit genetic groups under heat stress were detected.

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RESUMO -Este experimento foi realizado para comparar as medidas objetivas e subjetivas da carcaça de 36 cordeiros, 18 da raça Corriedale e 18 mestiços (F1) Ile de France x Corriedale, abatidos com 30 a 32 kg PV. Os cordeiros foram desmamados aos 60 dias de idade, com 10 a 12 kg PV, e terminados em regime de confinamento total, no qual dispunham, à vontade, de uma ração com 15,0% PB e 70,0% NDT. Terminada a manipulação pós-abate e o resfriamento por 24 horas a 4°C, avaliações objetivas e subjetivas nas carcaças foram realizadas. Houve diferenças entre os grupos genéticos estudados somente quanto ao comprimento externo e interno da carcaça, tendo os cordeiros puros apresentado maiores valores para essas medidas. Entretanto, por meio da média geral constatada para a área do longissimus dorsi, foi observado que os dois grupos genéticos apresentaram a mesma quantidade de músculo na carcaça. As carcaças dos cordeiros mestiços (IF x C) foram consideradas de melhor conformação e apresentaram a mesma quantidade de gordura de cobertura que as de inferior conformação. Os genótipos estudados, de maneira geral, foram capazes de atender dois importantes requisitos: a exigência do mercado consumidor por carcaças que não apresentem excesso de tecido adiposo e a necessidade de pequena cobertura de gordura, para que a qualidade da carne não seja prejudicada.Palavras-chave: carcaça, carne ovina, cordeiro, cruzamento Effect of Objective and Subjective Measurements of Carcasses from Lambs Finished in FeedlotABSTRACT -This experiment was carried out to compare the objective and subjective measurements of carcasses from 18 Corriedale and 18 Ile de France x Corriedale lambs, slaughtered at 30 to 32 kg LW. The lambs were weaned at 60 days of age, with 10 to 12 kg LW, finished in feedlot, and were full fed a diet with 15,0% CP and 70,0% TDN. After post-slaughter manipulation and cooled for 24 hours at 4°C, the objective and subjective carcass evaluations were made. There were differences between the studied genotype groups only for carcass external and internal length. The straightbreds lambs presented higher values for those measurements. However, by the overall mean observed for the longissimus dorsi area, the genotype groups presented the same amount of muscle in the carcass. The crossbred lamb carcass (IF x C) were considered to have the best conformation and presented the same subcutaneous fat cover of that of pour conformation. The studied genotype groups, in overall, were capable to meet two important demand of meat market requirements for lean carcass but with small subcutaneous fat cover to conserve the meat quality.Key Words: carcass, lamb meat, lamb, crossbreeding Rev. bras. zootec., 29(1):306-311, 2000 1 Projeto financiado pela FAPESP. 2 Professor Adjunto do DPEA -FMVZ/UNESP -18618-000, Botucatu/ SP. Fax: (0XX14) 8207180. E. mail: e.r.siqueira@fca.unesp.br 3 Zootecnista -DPEA -FMVZ/UNESP -18618-000, Botucatu/ SP. IntroduçãoO estudo dos aspectos qualitativos das carcaças ovinas produzidas nas distintas regiões criatórias reves...