Desempenho e exigências de energia e proteína de bovinos de corte em pasto suplementados

Avaliou-se o efeito dos níveis de suplementação sobre o desempenho, as características de carcaça, a composição corporal e as exigências de energia e proteína de bovinos de corte sob pastejo. A área experimental constituiu-se de cinco piquetes formados com Brachiaria decumbens. Utilizaram-se 22 bovinos não castrados, com peso corporal médio inicial de 320kg e idade de 18 meses. Três animais foram abatidos ao início do experimento para servirem como referência. Dos 19 animais restantes, três foram designados ao grupo mantença (MT), os outros 16 foram distribuídos em quatro tratamentos: controle ou mistura mineral (MM), 1kg, 2kg e 3kg de suplemento ao dia. Observou-se aumento linear no consumo de matéria seca (CMS), energia digestível (CED) e energia metabolizável (CEM); o consumo de nutrientes digestíveis totais (CNDT) foi máximo para o consumo de 2,88kg de suplemento. O ganho médio diário (GMD) máximo, 0,91kg/dia, foi observado para o consumo de suplemento de 2,69kg/dia. Verificou-se aumento linear no peso corporal em jejum (PCJ), no peso de corpo vazio (PCVZ) e no peso da carcaça para os animais suplementados. Não foi observado efeito da suplementação sobre o rendimento da carcaça. Verificou-se aumento sobre a área de olho de lombo (AOL) e a espessura de gordura subcutânea (EGS), quando os animais não suplementados foram comparados com os suplementados. Não foi observado efeito para o comprimento da carcaça (CCA), nem para os rendimentos dos cortes comerciais. As exigências líquidas de energia e proteína apresentaram, respectivamente, aumento e redução com o aumento do PC dos animais. As exigências de energia líquida para mantença (ELm) foram de 85 kcal/PCVZ0,75. As exigências de energia metabolizável para mantença foram estimadas em 130,08 kcal/PCVZ0,75. A suplementação de bovinos no período de transição águas-seca aumenta o consumo de MS e energia, promovendo aumento do ganho de peso dos animais

Examination of factors influencing the voluntary food intake of grass silage by ruminants

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN004088 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The effect of management system at lambing and flock genetics on lamb output on lowland sheep farms

Systems of lowland sheep production in the UK and Ireland are labour intensive with survey data indicating an average level of labour input of 6.0 to 8.0 hrs/ewe/year (Connolly, 2000). With declining returns from lamb production, management options with reduced labour requirements, such as outdoor lambing, need evaluation. Flock genetics may also influence labour requirements and determine the effectiveness of grass-based lambing systems. Therefore, the aims of current study were firstly to evaluate the effect on lamb output of controlled grass-based lambing systems compared with housing ewes in late pregnancy and lambing indoors and secondly to examine the effect of crossbred ewe genotype and ram breed on lamb output with grass-based and indoor lambing systems.</jats:p

The effect of crossbred ewe type and ram genotype on lamb output and carcass quality

In view of the stratified nature of the sheep industry, changes in breeding policies in the hill sector impinge on the performance of the lowland sector. Carson et al (2000) investigated the effect of choice of ram and ewe breed on lamb output and carcass quality in the hill sheep sector. First cross (F1) ewes were produced as a result of crossing Scottish Blackface and Cheviot ewes with a range of ram breeds. The primary objective of the present study was to provide information on the performance of these crossbred females in terms of lamb output and carcass quality and thus determine the impact of changing hill genetics on all strata of the sheep industry. Within the terminal sire breeds significant improvements in lean growth potential have been made through genetic improvement schemes. The secondary objective of this study was to provide information on the effects of using high lean growth index rams on lamb growth and carcass quality.</jats:p

Relationship between dry matter and fibre degradation characteristics of silage and silage intake in steers

The lower intake of silage relative to fresh grass or hay from the same sward has been attributed to the end-products of fermentation, both in the silo and in the rumen (Thiago, Gill and Dhanoa, 1992). However, research at this Institute has indicated that the relationships between silage fermentation products and intake are poor (R2&lt;0.10) (Steen et al, 1995). Thorton and Minson (1972) noted that the voluntary intake of forage (mainly dried forage) was inversely related to retention time in the rumen. The relationship between breakdown of dried forages (e.g. hay and straw) in the rumen and intake has been extensively studied, whilst the relationship between rumen degradation of silages and intake has not been studied to the same extent. The aim of the current study was to determine if there is a relationship between silage intake and degradation characteristics in the rumen, with a view to providing a better understanding of the control of silage intake.</jats:p