Effect of production phase on growth, enzyme activities and feed selection of broilers raised on vegetable protein diet.

This study consisted of two experiments, conducted to assess the impact of phase at which vegetable protein (VP) diets are introduced to broiler chicks, and preference of birds for diets based on soybean or canola meal (CM). Two hundred and ten day-old Cobb 500 chicks were randomly distributed into five dietary groups in the main experiment. One group was fed on animal protein (AP) diet all through to 21 days of age; two other groups were started on AP diet for 7 days and then switched to diets containing soybean meal (AP-SBM) or AP-CM, while two other diets (SBM-AP and CM-AP) were started on one of the VP diets for 7 days and then switched to AP diet. A sub-experiment on thirty birds raised on a commercial diet to 7 days was used in a feed selection test to quantify the preference of birds for the diets containing mainly CM or SBM. Chicks were reared under similar care and management conditions and the diets were iso-caloric and iso-nitrogenous. Results of the main experiment showed that chicks on CM-AP diet ate more (p<0.05) than those on the other diets up to day 7. Body weight gain was highest (p<0.001) on the AP-SBM diet while birds on the CM-AP diet weighed the least at 7 d. Feed intake, body weight gain, feed conversion ratio, mortality, bone growth, visceral organ development, and activities of digestive enzymes were similar between the groups from hatch to 21 days of age. Results of the second sub-experiment showed that chicks preferred the CM-based diets to the SBM-based diets at 8 to 14 d (p<0.001) and 15 to 21 d (p<0.01) when given a choice. Overall, the birds were not affected by the nature of the starter diet although they tended to prefer the canola to soybean diets.

Grazing behaviour of dairy cows on biodiverse mountain pastures is more influenced by slope than cow breed.

The aim of this study was to determine how cows with different genetic merit behave and perform when grazing biodiverse and heterogeneous mountain pastures with different slopes. Three groups of 12 cows in late lactation, each composed of four Holstein, four Montbéliarde and four Valdostana Red Pied cows, breeds of increasing presumed robustness and decreasing milk yield (MY) potential. Cows grazed without concentrate either on a low-diversity flat pasture or on two species-rich mountainous pastures having slopes of either 7° or 22°. Milk yield, BW and grazing behaviour were monitored two times in the first and once in the second grazing cycle. Cows of different breeds had similar behaviour on all pastures. The Montbéliarde cows performed close to their production potential; Holstein and Valdostana cows produced less milk than anticipated. No breed difference in terms of BW loss was found. The Valdostana cows exhibited the least selective behaviour with respect to plant species and plant growth stage. Still, all cows searched for the most palatable vegetation regardless of pasture diversity. On the steep pasture, cows optimised the trade-off between ingesting and saving energy to obtain feed. They remained longer at the lowest zone and selected forbs, whereas cows on the flatter pasture went to the upper zone to select grasses. The present study gave no evidence for a superior short-term adaptation to harsh grazing conditions through an optimised feeding behaviour of the Valdostana breed compared to Montbéliarde and Holstein cows.

Feed selectivity of laying hens undergoing different beak trimming in two rearing systems / Seletividade alimentar de galinhas poedeiras submetidas a diferentes métodos de debicagem em dois sistemas de criação

ABSTRACT: The present research was conducted to evaluate whether different beak trimming methods and rearing systems affected the feed selectivity of laying hens. A total of 178 Hy-line Brown laying hens in the growing phase and 120 hens in the production phase were divided in a factorial arrangement (2 x 3), with two rearing systems (floor and cages) and three beak trimming methods: without beak trimming (control), hot-blade beak trimming, and infrared beak trimming, with four replicates. Laying hens were feed with isonutritive diets. Samples were collected from feed orts and feed provided, with a subsequent analysis of dry matter, crude energy, crude protein, mineral matter, geometric mean diameter and geometric standard deviation. The results were subjected to the error normality test, analysis of variance and the Fisher-Snedecor (P<0.05) and Duncan tests (P<0.05). The beak trimming methods evaluated were not sufficient to prevent feed selection in laying hens. However, in the growing phase, hot-blade beak trimming reduced feed selection capacity of laying hens more than did infrared beak trimming. The cage system favored feed selection, both in the growing and production phases.

RESUMO: O presente trabalho foi conduzido para avaliar se diferentes métodos de debicagem e sistemas de criação afetam a seletividade alimentar de galinhas poedeiras. Foram utilizadas 178 aves na fase de recria e 120 aves na fase de produção, da linhagem Hy-line Brown, divididas em um delineamento experimental em esquema fatorial (2x3), com dois sistemas de criação (piso e gaiolas) e três manejos de bico: sem debicar (controle), debicagem por lâmina quente e radiação infravermelha, com quatro repetições. As aves foram alimentadas com rações isonutritivas e foram coletadas amostras das sobras e das rações controle, com posterior análise da matéria seca, energia bruta, proteína bruta, matéria mineral, diâmetro geométrico médio e desvio padrão geométrico. Os resultados foram submetidos ao teste de normalidade dos erros, análise de variância e aos testes de médias de Fisher-snedecor (P<0,05) e Duncan (P<0,05). Os métodos de debicagem avaliados não são suficientes para impedir a seleção de alimento de galinhas de postura. No entanto, na fase de recria, a debicagem por lâmina quente reduz a capacidade de seleção das galinhas, em relação à debicagem por infravermelho. O sistema de criação em gaiolas favorece a seleção de alimento pelas galinhas poedeiras, tanto na fase de recria quanto na fase de produção.