Fatty acid and energy metabolism in broiler chickens fed diets containing either beef tallow or an oil blend.

The hypothesis tested was that the feeding of n-6 polyunsaturated fatty acids (PUFA) results in more whole-body fatty acid oxidation than the feeding of saturated fatty acids (SFA). It was reasoned that the increased fatty acid oxidation would be associated with enhanced whole-body energy expenditure and stimulated de novo fatty acid synthesis. To put the hypothesis to the test, broiler chickens were fed diets containing either beef tallow as source of SFA or an oil blend as source of n-6 PUFA. The broilers either had free access to their diet or were fed a restricted amount. Seven-day-old, male broiler chickens were used; they were kept individually in cages from 1 to 4 weeks of age. In the birds fed ad libitum, the n-6 PUFA diet reduced average daily feed intake (ADFI), but did not significantly affect average daily weight gain (ADG) and the feed:conversion ratio (FCR). The lower ADFI on the n-6 PUFA diet was associated with a higher apparent digestibility of total fatty acids. The ratio of deposition in the body to intake of digestible total PUFA, which reflected n-6 PUFA, was significantly decreased by the n-6 PUFA diet, pointing at preferentially increased n-6 PUFA oxidation on the n-6 PUFA diet. The ratio for n-9 monounsaturated fatty acids (MUFA) was higher than 1.0, which agrees with net de novo synthesis, but the n-6 PUFA diet induced a lower value than did the SFA diet. Feeding either the n-6 PUFA or SFA diet did not influence energy expenditure expressed as percentage of energy intake. This study supports the idea that dietary n-6 PUFA instead of SFA are preferentially oxidized, but no proof was obtained for enhanced energy expenditure and contrary to the hypothesis put forward, the n-6 PUFA diet depressed de-novo fatty acid synthesis.

Digestion and deposition of individual fatty acids in growing-finishing pigs fed diets containing either beef tallow or sunflower oil.

The apparent digestibility and deposition in carcass of individual dietary fatty acids (FA) were determined in growing-finishing pigs fed diets containing either beef tallow or sunflower oil. The beef tallow was rich in saturated FA (SFA) and the sunflower oil had a high content of polyunsaturated FA (PUFA). A total of 39 barrows was used. The experimental diets contained 5% (w/w) of the variable fat source and were fed ad libitum. The dietary fat type had no effect (p > 0.05) on growth performance, even though the apparent digestibilities of crude fat and crude protein were higher (p < 0.05) in the animals fed sunflower oil. The pigs fed the sunflower oil diet showed higher apparent digestibilities (p < 0.05) of the sum of SFA, monounsaturated FA (MUFA) and PUFA, but had a lower digestibility (p < 0.05) of stearic acid. The intakes of individual digestible FA were derived feed intake data, FA contents of the diets and the digestibility of individual FA. For the entire feeding period of 13 weeks, the ratio of deposition in carcass to intake of digestible FA was increased (p < 0.05) for palmitic and stearic acid in the pigs fed sunflower oil, but the ratios for oleic acid and linoleic acid were decreased (p < 0.001). In the pigs fed sunflower oil instead of beef tallow, the deposition:intake ratio was raised for the SFA (p < 0.001), but diminished for the MUFA (p < 0.05). The calculated minimum de novo synthesis of SFA was increased (p < 0.05) and that of MUFA decreased (p < 0.05) in the pigs fed sunflower oil. It is concluded that the feeding of a diet with sunflower oil instead of beef tallow improved apparent digestibility of SFA, MUFA and PUFA, increased the deposition:digestible intake ratio for SFA, but lowered that for MUFA and PUFA.

Macronutrient digestibility in Kadon pigs fed diets with isonitrogenous amounts of various carbohydrate sources.

In this experiment, the apparent digestibility of diets with isonitrogenous amounts of different carbohydrate sources was determined in Kadon pigs, which are native to the North-East of Thailand and typically kept on small-holder farms. Eight male and eight female pigs were used in a 4 x 4 Latin square design with diets containing either ground corn (GC), rice bran (RB), broken rice (BR) or cassava chips (CC). The diet with BR induced the highest digestibilities for protein and energy, but also had the highest ingredients costs. In essence, the diet with CC had produced the second highest digestibilities, whereas this diet was 18% less expensive than the diet with BR. Nitrogen (N) retention, expressed as % of N intake, was highest in the pigs fed the diet containing BR. The outcome of this study may contribute to the formulation of pig diets when aiming at optimizing ingredient costs and growth performance.

Influence of amount and type of dietary fat on deposition, adipocyte count and iodine number of abdominal fat in broiler chickens.

This study described the relation between the type and amount of dietary fat on the deposition of abdominal fat by broiler chickens. It was hypothesized that at higher fat intakes, the well-known lowering effect of polyunsaturated fatty acids on the deposition of abdominal fat would be diminished. Experimental diets were formulated to contain three levels of added fat (3%, 6% and 9%). Each level had different proportions of the saturated fatty acids (SFA) and unsaturated fatty acids (UFA) by installing the ratios of 1:1, 1:2, 1:3, 1:4 and 1:5 with the use of tallow and soybean oil. Arbor Acres chicks, aged 7 days, were fed one of the 15 experimental diets until they were aged 42 days. Feed and water were provided ad libitum. There was no systematic effect of the dietary fat type and the amount on the weight gain and the feed intake. The lowest SFA:UFA ratio of 1:5 produced the lowest feed conversion rates, irrespective of the amount of the fat in the diet. The abdominal fat deposition was similar in the birds fed on diets containing either 3% or 6% added fat, but deposition was lower than in those fed 9% fat. A decrease in the SFA:UFA ratio of the diet was associated with a dose-dependent decrease in abdominal fat, irrespective of the amount of fat in the diet. This observation leads to the rejection of the hypothesis stated above. A decrease in the dietary SFA:UFA from 1:1 to 1:4 caused a decrease in the number of the fat cells per surface unit of breast meat. It is concluded that an increased intake of soybean oil at the expense of tallow reduced the abdominal fat deposition and the number of fat cells in the breast meat of broiler chickens.