RESUMO

This study evaluated the effects of chromium yeast (Cr yeast) and two apparent metabolizable energy (AME) levels on productive performance, egg quality, and lipid and carbohydrate metabolism in laying hens. A total of 192 Bovans White laying hens at 47 weeks of age were randomly assigned to eight dietary treatments (six replicates each) in a 4 × 2 factorial arrangement: four levels of supplemental Cr (0, 0.2, 0.4, and 0.8 ppm as Cr yeast) and two AME levels (2,780 and 2,900 kcal AME kg−1). No significant effect of Cr yeast supplementation on feed intake, egg weight, egg production, intact eggs, egg mass, feed conversion ratio, or egg quality was observed. Egg quality parameters and Cr content in the yolk were not affected by dietary treatments. Plasma glucose and lipid levels were not influenced by either Cr yeast or AME levels used in this study. However, Cr yeast supplementation improved yolk percentage and hepatic glycogen content. The inclusion of Cr yeast at 0.2 and 0.4 ppm induced the highest hepatic glycogen content with the energy levels 2,900 and 2,780 kcal AME kg−1, respectively. Laying hens fed 2,900 kcal AME kg−1 showed the highest abdominal fat. The results observed in the present study support the hypothesis that the lack of positive effects of Cr yeast supplementation on production performance and egg quality may be related to good management practices, as the birds were not subjected to stressful conditions.

Assuntos

RESUMO

O efeito da temperatura e o efeito do enriquecimento do piso de gaiola sobre o bem-estar de coelhos em crescimento foram avaliados. Quarenta e oito coelhos do grupo genético Botucatu, desmamados aos 35 dias de idade, foram alojados em Câmara Climática, quatro por gaiola (1,00 x 0,60 x 0,40m), em 12 gaiolas que tinham (ou não) metade do piso coberto com cama de palha. As gaiolas foram instaladas metade em sala com temperatura ambiente e metade em sala resfriada. Os animais tiveram livre acesso à ração balanceada e à água nos dois tipos de piso. Para se avaliar o bem-estar, foram realizadas cinco observações de 24 horas cada, uma por semana, sendo registradas as freqüências dos comportamentos: lúdico, estereotipado, exploratório, cuidados corporais e interação e comparadas entre gaiolas enriquecidas ou não nas duas salas. A média de temperatura e a média de umidade relativa do ar foram: 23,6°C e 78,7 por cento na sala natural e 20,6°C e 71,0 por cento na sala resfriada. O comportamento lúdico foi mais freqüente nas gaiolas enriquecidas (7,6 vs 4,3 por cento sala natural e 7,8 vs 3,8 por cento sala resfriada, P<0,01) e as estereotipias foram mais freqüentes nas gaiolas sem enriquecimento (4,4 vs. 2,7 por cento sala natural e 2,1 vs 1,1 por cento sala resfriada, P>0,01). Coelhos mantidos em temperatura natural preferiram a grade à cama de palha (77,9 vs. 22,1 por cento, P>0,01), enquanto na sala resfriada eles não mostraram preferência em relação ao piso (45,9 vs 54,1 por cento, P=0,41). Em sala resfriada, o enriquecimento com palha favoreceu o bem-estar animal.

The effects of temperature and cage floor enrichment on the welfare of growing rabbits were evaluated. Forty-eight rabbits from the Botucatu genetic group, weaned at 35 days of age were housed in an Environmental Chamber, four per cage (1.00 x 0.60 x 0.40m), in 12 cages that had (or not) half of the floor covered with litter straw. The cages were housed half in a room temperature chamber and half in a refrigerated chamber. Animals had free access to a balanced feed and water in the two types of floor. In order to evaluate welfare, five 24-hour observations were carried out, one per week, to register the frequencies of the following behaviors: ludic, stereotypic, exploratory, self-grooming and interactions, and to compare them between enriched and non-enriched cages from the two chambers. The average temperatures and relative humidities were 23.6°C and 78.7 percent in the room temperature chamber and 20.6°C and 71.0 percent in the refrigerated chamber. The ludic behavior was more frequent in the enriched cages (7.6 vs. 4.3 percent Room Temperature Chamber and 7.8 vs. 3.8 percent Refrigerated Chamber, P<0.01) and the stereotypies in the non-enriched cages (4.4 vs. 2.7 percent Room Temperature Chamber and 2.1 vs 1.1 percent Refrigerated Chamber, P<0.01). Rabbits kept at room temperature preferred the wire net floor over the litter straw (77.9 vs. 22.1 percent, P<0.01), whereas in the refrigerated chamber they did not show preference regarding floor types (45.9 vs. 54.1 percent, P=0.41). In the refrigerated chamber, cage floor enrichment favored animal welfare.