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Fat feeding in lactating buffaloes
 Haq Nawaz

In Pakistan , buffaloes are the major milk producing animals and contribute about 73 per cent of the total milk production. The productivity of buffalo is affected by many physiological and environmental factors. Among these, feeding and nutrition are of prime importance. Buffalo milk contains higher contents of fat and solids-not-fat, reflecting higher energy demands than those for other cattle.

High yielding dairy animals experience a substantial energy deficit in early lactation while high concentrate diets utilized to overcome this deficit tend to depress milk fat percentage. The first trimester of lactation is particularly critical because peak intake trails peak milk yield by as much as 8 weeks and excessive loss of body reserves at this time can impair reproductive performance of the animal and can depress total lactation milk yield.

Energy intake of high yield animals can be increased by feeding either more concentrate or supplemental fat. Feeding large amounts of concentrate alters ruminal fermentation and often depresses milk fat synthesis. Addition of fat sources may improve the energy status of high yield dairy animals. Increasing fat content of diets increases energy density.

Thus, if the weight of feed eaten remains constant, energy intake is increased. High yielding animals are unable to consume enough energy from traditional feeds to meet their requirements during early lactation. Supplemental sources of dietary fat such as whole oil seeds and tallow, are commonly used in attempts to provide extra energy to early lactating animals to enable them to achieve their genetic potential for milk production.

The challenge for dairy nutritionists is to formulate diets for lactating dairy animals that will maintain health and maximise milk yield while minimising the cost. There has been an increasing interest in feeding fats to dairy cows and a wide variety of fat sources are used to increase the energy density of diets fed to cows in early lactation or to high yield dairy animals in negative energy balance. Thus, use of fats and oils to increase energy density of diets for dairy animals has gained wide acceptance.

Fats and oils are essential constituents of human and animal food and are derived from animal, vegetable and marine sources. They are also carriers of very important biological materials like essential fatty acids and phospholipids. Annual production of vegetable oils and animal fat in
Pakistan is 420,000 and 120,000 million tonens, respectively. Vegetable oils are being consumed mainly by the human population but by-products of this industry and animal by-products such as tallow and poultry fat are used in manufacturing of cosmetics, detergents, greases and paints. It is desirable to maximise the use of low cost fat sources in dairy animals. A study was undertaken to determine the physico-chemical characteristics and fatty acid composition of fats and oils available in Pakistan so that these could be used in the diets of lactating dairy animals as energy sources.

In phase I of the experiment, four isonitrogenous and isocaloric experimental diets were fed to lactating buffaloes as total mixed ration containing no added fat or having tallow, poultry fat or mustard oil, at 3 per cent of diet dry matter. In phase II of the experiment tallow was added in the rations at 2, 4 and 6 per cent of the diet dry matter.

Intake of dry matter decreased in buffaloes fed supplemental tallow and poultry fat as compared to those fed diets containing no fat or mustard oil. Higher energetic efficiency of milk yield was observed in buffaloes fed tallow-supplemented diet compared to those fed diets containing poultry fat and mustard oil. Daily milk production was higher for buffaloes on diets containing different sources of supplemental fat. Milk fat percentage was higher for lactating buffaloes consuming supplemental tallow compared to those fed diets containing other two sources of fat. Gain in body weight was higher for those assigned to experimental diets versus those consuming the control diets.

Dry matter digestibility, blood pH, concentrations of glucose, total cholesterol, triglyceride and total blood lipids did not vary due to addition of different fat sources in the rations of lactating buffaloes. Rumen pH did not differ significantly, whereas, acetate concentration was significantly lower in buffaloes fed different sources of supplemental fat versus those fed control diet. Milk production cost (Rs/kg) was significantly lower for buffaloes fed supplemental tallow. But the production cost increased with increased level of tallow in the diet. Income in relation to feed cost was higher for buffaloes fed supplemental tallow and poultry fat compared to those fed the controlled diet. The diet containing mustard oil manifested a decline in income in relation to feed cost.

In phase II, intake of dry matter was lower but daily milk yield and milk fat contents were higher for buffaloes consuming diets containing different levels of supplemental tallow. The digestibility of dry matter increased significantly at 4 per cent dietary tallow, beyond which it manifested a decline. Blood pH and concentrations of glucose did not vary significantly due to addition of tallow to the ration upto 6 per cent. The concentrations of total cholesterol, tri-glyceride and total blood lipids did not vary significantly due to the addition of 2 per cent tallow beyond which a significant rise in these metabolites in the blood was observed. Rumen pH and concentration of butyrate differed non-significantly but concentrations of acetate decreased and propionate increased due to addition of tallow in the diets. The acetate to propionate ratio decreased as the level of tallow increased in the diet. Milk production cost (Rs/kg) was lower for buffaloes fed supplemental tallow. However, the production cost increased with increased level of tallow in the diet. Income over feed cost was highest for buffaloes fed 2 per cent dietary tallow beyond which it trended to decline.

The results of the present study indicate that some of the physico-chemical characteristics of fats/oils can affect the performance of lactating buffaloes. The comparison of different fat sources shows that tallow is an economical source of energy for supplementing in the diet of lactating buffaloes, whereas mustard oil causes a decline in income-to-feed cost ratio.

Tallow upto 4 per cent of diet dry matter appears to be a suitable fat supplement as an energy source for lactating buffaloes. The change in fatty acid composition of buffalo's milk fat due to fat supplementation seems to be favourable for human health.