The objectives of this study were to determine the effects of oral Gln supplementation on growth performance, intestinal morphology, and expression of heat shock protein (Hsp) 70 in weaning piglets. A total of 65 piglets after weaning at 21 d of age (d 0) were used in this experiment. Five piglets were randomly selected and euthanized initially at d 0 to determine baseline values for the expression of Hsp70 in the small intestine. The remaining piglets were randomly assigned to 1 of 2 treatments and received 0 or 1 g of oral Gln/kg of BW every 12 h. After piglets were humanely killed at d 3, 7, and 14 postweaning, the duodenum, jejunum, and ileum of piglets were sampled to evaluate intestinal morphology and the expression and localization of Hsp70. The results indicated that oral Gln supplementation increased plasma concentrations of Gln compared with those in control piglets (P < 0.05). Average daily gain and ADFI were greater in piglets orally supplemented with Gln than in control piglets during the whole period (P < 0.05). The incidence of diarrhea in piglets orally supplemented with Gln was 24% less than (P = 0.064) that in control piglets at 8 to 14 d after weaning. The weights of the jejunum and ileum were greater in piglets orally supplemented with Gln compared with those of control piglets relative to BW on d 14 postweaning (P < 0.05). The villus height and the villus height:crypt depth ratio in the jejunum and the ileum were greater in piglets receiving oral Gln on d 14 postweaning (P < 0.05) than in control piglets. These results indicate that Gln supplementation can influence the intestinal morphology of weaned piglets. The expression of hsp70 mRNA and Hsp70 proteins in the duodenum and jejunum was greater in piglets supplemented with Gln than in control piglets (P < 0.05). However, Gln supplementation had no effect on the expression of hsp70 mRNA and Hsp70 proteins in the ileum. Moreover, the localization of Hsp70 in the cytoplasm indicated that Hsp70 has a cytoprotective role in epithelial cell function and structure. These results indicate that Gln supplementation may be beneficial for intestinal health and development and may thus mitigate diarrhea and improve growth performance. The protective mechanisms of Gln in the intestine may be associated with the increase in Hsp70 expression.

A dose-response experiment with 5 analyzed dietary crude protein (CP) levels (17.61, 19.73, 21.58, 23.24, and 25.32%) was conducted to investigate the effects of low-protein diets on growth performance and carcass yields of French meat quails from 15 to 42 d of age. All diets were formulated to contain a similar dietary energy level and amino acid profile. A total of 400 fifteen-day-old French quails were divided into 5 experimental treatments and each treatment contained 4 replicate pens of 20 birds (10♂+10♀). At 42 d of age, weight gain, feed intake, CP intake, feed/gain, and the yields of breast part with bone, leg part with bone, and liver of quails from each pen were measured. The results showed significant effects of the low-CP diets on CP intake, weight gain, feed intake, and feed/gain at different experiment periods except for the sixth wk of age (P < 0.05). In addition, as dietary CP decreased from 25.32 to 17.61%, feed intake and feed/gain were increased linearly (P < 0.05), whereas CP intake showed the opposite trend and decreased gradually. On the other hand, the carcass yields of quail were not influenced by reducing dietary CP at 42 day of age (P > 0.05). Based on broken-line regression, 23.0%, 22.5%, and 20.4% were the minimum dietary CP to keep weight gain similar to the quails fed with 25.32% CP diets during the third, fourth, and fifth wk of age, respectively. In summary, with crystalline amino acid supplementation based on a similar amino acid profile, it was possible to formulate the low-protein diets containing about 22.0% CP for growing meat quails without adverse effects on growth and carcass yields of meat quails.

A total of 24 four-month-old Liuyang Black wether goats (10±0.2 kg) were allotted to two diets based on wheat and maize to investigate effects of starch sources on the growth performance and meat quality. The experimental period lasted for 100 days, including 10 days for adaptation. Five representative goats from each group were selected for slaughter on the last experimental day. The final body weight and body weight gain of goats in wheat group were lower than those of goats in maize group (P<0.05), however, the marbling score of the Longissimus dorsi of goats in wheat group was greater than that of goats in maize group (P<0.05). Fatty acid composition of Longissimus dorsi muscle was also different between wheat group and maize group, for example, the proportion of C14:0 in Longissimus dorsi muscle of goats in wheat group was greater than that of goats in maize group (P<0.05), and the proportion of C18:3 in Longissimus dorsi muscle of goats in wheat group was smaller than that of goats in maize group. Results indicate that growth performance of the goats Journal of Animal and Feed Sciences, 21, 2012, 587-598 588 MEAT QUALITY OF GOATS AND STARCH SOURCES fed the diet based on maize was better and the proportion of 18:3 fatty acids and marbling score of Longissimus dorsi muscle was smaller in comparison with the goats fed the diet based on wheat.