Expression of genes related to liver fatty acid metabolism in fat-tailed and thin-tailed lambs during negative and positive energy balances.

Fat-tailed sheep breeds can tolerate periods of negative energy balance without suffering from elevated concentration of plasma non-esterified fatty acid (NEFA). This ability was attributed to unique metabolism of fat-tailed adipose depot, whereas role of liver as an influential organ in fatty acid metabolism was not evaluated yet. Hence, current study was conducted to evaluate the effects of negative and positive energy balances on liver expression of genes related to fatty acid metabolism in fat-tailed and thin-tailed lambs. Lambs experienced negative (21 days) and positive (21 days) energy balances and were slaughtered at the beginning and end of negative energy balance and at the end of positive energy balance. Real-time quantitative polymerase chain reaction (RT-Q-PCR) was conducted to evaluate changes in gene expression. Expression of diglyceride acyltransferase 1 (DGAT1), 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) and apolipoprotein B (APOB) was not affected by genotype, energy balance and their interaction. Expression of carnitine palmitoyltransferase 1 (CPT1) was significantly higher in liver of fat-tailed comparing to thin-tailed lambs regardless of energy balance (p < 0.02). Catalase mRNA abundance was increased in response to negative energy balance (p < 0.02), and severity of this enhancement was higher in fat-tailed lambs (p < 0.06). Expression of CPT1 was positively correlated with expression of HMGCS2 in both fat-tailed (p < 0.05) and thin-tailed lambs (p < 0.002); however, the correlation was weaker in fat-tailed lambs (0.72 vs. 0.57, respectively, for thin-tailed and fat-tailed lambs). There was a positive correlation between DGAT1 and APOB genes expression in fat-tailed lambs (0.94; p < 0.001), whereas this correlation was not observed in thin-tailed lambs. Results demonstrate that liver of fat-tailed lambs has higher capacity for metabolism of mobilized NEFA exposed to liver during negative energy balance.

Comparison the Zn-Threonine, Zn-Methionine, and Zn Oxide on Performance, Egg Quality, Zn Bioavailability, and Zn Content in Egg and Excreta of Laying Hens.

The experiment was conducted to investigate the effect of supplementary zinc-threonine (Zn-Thr), zinc-methionine (Zn-Met), and zinc oxide (ZnO) on the laying performance, egg quality, Zn content in egg and excreta. One hundred and sixty hens (Hy-Line W36) were randomly divided into 10 treatments with 4 replications of 4 hens each. During the first 4 weeks, groups were fed a corn-soy basal diet without extra zinc (30.3 mg Zn/kg diet) to depletion storage zinc from the body and it was used as the control diet. During the ensuing 10 weeks from 36 to 45 weeks of age, 3 levels of 30, 60, and 90 mg Zn/kg were added to the diet by ZnO, Zn-Met, and Zn-Thr sources. Results showed that there were no significant differences between the experimental treatments in terms of egg weight, feed intake, eggshell weight, eggshell percentage, and albumen weight. In total experimental period, the supplementation of Zn-Met and Zn-Thr decreased feed conversion ratio and increased egg mass and egg production compared with ZnO 30 and 60 mg Zn/kg and control treatments (P < 0.05). The results showed that treatment effect on Zn content in egg and excreta was significant (P < 0.05). It is concluded that diets supplied with lower levels of organic Zn can maintain egg production performance, improve egg quality, enrich eggs, increase bioavailability, and reduce the negative effects of age on egg quality characteristics in laying hens compared with their oxide form.