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The purpose of this study was to evaluate the effect of protected fat and heat-extruded soybean meal on the lactation performance of Holstein cows. Twenty-four cows, consisting of 20 lactating cows and 4 rumen-fistulated dry cows, were randomly allocated into four groups with 5 lactating cows and 1 fistulated cow in each group. A replicated 4×4 Latin square design with four 21 day periods, including 14 days of adaptation and 7 collection days within each period was employed. The experiment was a 2×2 arrangement, with or without heat-extruded soybean meal and protected fat inclusion. The dietary treatments consisted of supplements of (a) soybean meal (the control), (b) heat-extruded soybean meal, (c) protected fat, and (d) heat-extruded soybean meal and protected fat. The results showed that there were no significant differences in feed intake, milk yield, milk protein content, milk lactose content and body weight change between the dietary treatments. However, cows supplemented with protected fat showed a significantly increased (p<0.05) milk fat yield, 3.5% FCM and total solid yield. The increase in undegradable intake protein (UIP) via heat extruded soybean meal supplement significantly decreased the urea nitrogen concentration in the blood (p<0.05). Dietary fat inclusion significantly increased the blood cholesterol concentration (p<0.01) and decreased the ruminal pH value (p<0.01). Increased dietary UIP significantly decreased the ammonia nitrogen concentration in the rumen (p<0.01), but did not significantly influence the pH and VFA molar percentage in the rumen. It appears that dietary protected fat inclusion could improve milk fat and solid content. Increased dietary undegradable intake protein through heat extruded soybean meal did not improve milk yield. But it could alleviate the adverse effect of decreased milk protein due to dietary fat supplementation. Increased UIP could also decrease the ammonia nitrogen concentration in the rumen and plasma urea nitrogen concentration in the blood.

This study investigated related traits of lipid metabolism in plasma and liver of layer Tsaiya ducks. Each of 60 ducks was randomly allocated into an ad libitum feeding and a three‐day fasting group during the growing period (8–12 weeks old) and during the initial laying period (26–30 weeks old; 10–14 weeks from the onset of laying), respectively. Results indicated that, even under ad libitum conditions, Tsaiya ducks had high concentrations of plasma glycerol and ketone bodies. Plasma triacylglycerol (TG) contents of laying ducks were approximately seven‐fold higher than those of growing ducks. Contents of liver fat and ketone bodies, plasma phospholipid and non‐esterified fatty acid (NEFA) concentrations were higher in the laying period than in the growing period. The lipogenesis‐related traits, including blood glucose, plasma TG and phospholipid concentrations, were significantly decreased by fasting (P < 0.05). In contrast, the lipolysis‐related traits, including plasma NEFA, glycerol and ketone body concentrations, were significantly increased by fasting (P < 0.05). After fasting, body and liver weights of ducks and contents of abdominal fat and liver TG were significantly decreased (P < 0.05); conversely, concentrations of liver ketone bodies were markedly increased (P < 0.05). This study indicated that fasting depressed lipogenesis and increased lipolysis in Tsaiya ducks. In addition, in laying ducks, lipogenesis was more active than in the growing ducks. © 1999 Society of Chemical Industry

No abstract

The study investigated the lipid metabolism of Tsaiya ducks under fasting and ad libitum feeding conditions. Sixty Tsaiya ducks in their growing period (8-12 wk-old) and sixty Tsaiya ducks in their laying period (26-30 wk-old, 10-14 weeks after the onset of laying) were randomly divided into ad libitum feeding and 3-day fasting groups. The activities of lipid metabolism related enzymes were determined. Experimental results indicated that fasting depressed the activities of lipogenesis related enzymes such as fatty acid synthetase and NADP-malic dehydrogenase in both periods (p<0.05). Fasting also increased the activities of liver fatty acid βoxidation enzymes (p<0.05). However, the activities of lipoprotein lipase in adipose tissue, heart and ovarian follicle in both periods and the hormone-sensitive lipase of adipose tissue in the growing period were decreased by fasting (p<0.01).