Abstract
An experiment was conducted to determine the effects of different dietary crude protein (CP) levels on growth performance, nutrient utilization, small intestine protease activity and immunity index of weaner to 2 month-old New Zealand rabbits. Eighty weaner rabbits were allocated in individual cages to five treatments in which they were fed diets with CP at 14%, 16%, 18%, 20% and 22%, respectively. The growth performance and nutrient digestibility of rabbits increased firstly when dietary CP increased, then decreased. The average daily gain was the highest and feed conversion rate was the lowest when dietary CP reached 20%, namely 34.9 g/d and 2.74:1, respectively. Maximum CP digestibility was 72.1% in the 18% CP group, maximum crude fiber digestibility of 28.4% occurred in the 16% CP group and was significantly different from other treatments (p 0.05), and was highest for 20% CP treatment (1.5 g/d). The effect of CP level on the rate of digestible nitrogen (DN) converted RN was small. The spleen index, thymus index, chymotrypsin and trypsin activities in small intestine were highest when dietary CP was 16%, which were 1.0, 2.8, 15.7 U/g and 125.7 U/g, respectively. There was no significant difference among treatments (p>0.05). According to the above results, the appropriate dietary CP level from weaner to 2 month-old meat rabbits was 18-20%.
Highlights
Eighty weaner rabbits were allocated in individual cages to five treatments in which they were fed diets with crude protein (CP) at 14%, 16%, 18%, 20% and 22%, respectively
The objectives of the research were to examine the effects of different dietary CP levels on growth performance, nutrient utilization, small intestine protease activity and immunity index of weaner rabbits, and to determine the appropriate dietary CP level in weaner to 2 month-old meat rabbits
Eighty weaned New Zealand rabbits were rabbits according to their respective proportions of body randomly allocated to five groups according to average body weight, with sixteen rabbits per group
Summary
Several authors have studied the total amino acid requirements for rabbits on a dose-response basis (de Blas, 1998). Recent studies (Taboada et al, 1994,1996; de Blas et al, 1996) have determined the lysine, sulphur and threonine requirements. Results for growth were consistent with those obtained by Moughan et al (1988) based on amino acid composition of the whole body. It is believed that the dietary crude protein requirement of growing rabbits is. Reported the appropriate crude protein level for meat rabbits was 18%-22%. Abdella (1988) indicated that body gain, protein digestibility, slaughter performance and economy benefits were the greatest when the dietary crude protein level was 16%. Wang (1991) pointed out that the average daily gain, feed conversion rate and slaughter rate were the best when the dietary crude protein level was 15.3%-17.9%
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