Effects of restricted feeding and re-alimentation of dietary protein or energy on compensatory growth of sheep

The study investigated the effects of re-alimenting dietary protein or energy on growth, carcass characteristics and meat eating quality parameters of sheep. Twenty-seven intact rams (~9 months; 11.3 ± 0.5 kg) were randomly divided into three groups. Each group was fed a maintenance diet (MT) containing, on dry matter (DM) basis, 105 g/kg crude protein (CP) and 8.4 MJ/kg DM metabolizable energy (ME) for 30 days. Thereafter, they were continually fed the same MT or re-alimented with a high protein diet (HP) containing 169 g/kg DM CP and 9.3 MJ/kg ME or a high energy diet (HE) containing 123 g/kg DM CP and 10.6 MJ/kg ME for an additional 30 days to determine the effects of re-alimentation of protein or energy on their growth performance and carcass characteristics. During the initial 30-day period, DM intake (DMI) and growth performance were similar among the three groups. However, upon re-alimentation, average daily gain (ADG) and feed efficiency of sheep re-alimented with HP were greater than those maintained continually on MT or re-alimented with HE. Sheep on HP had higher feed efficiency, ADG and heavier carcasses than those fed MT or re-alimented with HE during the whole 60-day period. Growth of most viscera was less responsive to the restriction-re-alimentation feeding regimen except for the weights of the lungs, heart and intestines. Meat from sheep re-alimented with HE had a more intense ‘sheepy’ flavour than those fed MT or re-alimented with HP, but juiciness and tenderness were not affected. The higher ADG of sheep re-alimented with protein may be related more to enhanced efficiency of feed utilization than to higher DMI.Keywords: average daily gain, feed restriction, nutrient utilization efficiency, visceral organ

Intestinal Nutrient-Gene Interaction: The Effect of Feed Deprivation and Refeeding on Cholecystokihin and Proglucagon Gene Expression

We tested the hypothesis that dietary components reaching the bovine small intestine influence the expression of genes that encode the gastrointestinal neuropeptides cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1). The amount of digesta reaching the intestine was manipulated during the experiment by withholding feed from five heifers fitted with ruminal, duodenal, and ileal cannulas for 48 h and then subsequent refeeding. Duodenal and ileal biopsies were collected using a fiber-optic endoscope. A Northern hybridization procedure was used to evaluate changes in gene expression. Blood concentrations of CCK and GLP-1 were determined with RIA. The data indicate that CCK blood concentration and mRNA abundance decreased during the period of feed deprivation, but they returned to predeprivation values within 16 to 24 h of refeeding. The GLP-1 blood concentration also decreased during feed deprivation and returned to predeprivation values within 4 to 8 h of refeeding, despite the fact that proglucagon mRNA abundance did not change significantly during feed deprivation and refeeding. These findings provide evidence that CCK and GLP-1 are released in response to nutrients that reach the small intestine and may be involved in the physiological process of digestion and possibly play a role in regulating feed intake in ruminants

Comparison of growth rates in the tissues of primal cuts of Canadian composites

Beef composites (C) have combined favourable traits of pure breeds. The objective was to compare the growth rates (GR) of muscle (M) and fat (F) in the primal cuts of serially harvested Beefbooster® C types (SM = C of small breeds, AH = C of Angus and Hereford and GLC = C with Gelbvieh, Limousin or Charolais terminal sires) from 274 - 456 days (d) of age to determine harvest times that reflect an increase M and a decrease F. Analysis of covariance obtained the slopes (GR/d) for M and F within each cut and C type. In the SM and AH the GR of overall F in all primal cuts exceeded that of M by 24.8 g/d and 4.91g/d respectively, while in GLC the gain of M exceeded that of F by 6.77 g/d. We suggest that the SM and AH could be harvested at least 30 d earlier than GLC thereby increasing the proportion of carcass M and decreasing F