Effect of the source of dietary fat on postweaning lipogenesis in lean and fat pigs.

Twenty-four male piglets weaned after 21 days, 12 of the Large White lean breed (LW) and 12 of the Alentejano fat breed (AL), have been used to compare the effects of genotype and source of dietary fat on the activities of enzymes involved in lipogenesis and on the composition of selected fatty tissues. During 4 weeks the piglets were fed isoenergetic and isonitrogenous experimental diets, containing 5 % of either olive oil or tallow. In AL piglets the acetylcoenzyme A carboxylase activity was three- and ninefold higher, the malic enzyme activity six- and fivefold, and the glucose-6-phosphate dehydrogenase activity was four- and fivefold higher in the dorsal subcutaneous and in the perirenal fat, respectively, than in LW piglets. In general, fatty tissues of the AL piglets contained a higher proportion of saturated fatty acids. Olive oil induced a significant increase in the activities of malic enzyme and glucose-6-phosphate dehydrogenase in both tissues, but only slightly increased the acetylcoenzyme A carboxylase activity in perirenal fatty tissues (p < 0.05). The fatty acid profile of the subcutaneous and of the perirenal fat was strongly affected by the composition of dietary fat. These observations showed that the source of dietary fat influenced markedly lipid metabolism and body composition since a very early age.

Influence of birth prematurity on colostrum composition and subsequent immunity of piglets.

Two groups of seven pregnant sows were farrowing either naturally after 111-114 days of gestation or prematurely after 109 days following an injection of 125 micrograms/animal of a prostaglandin analogue. Colostrum intake was controlled individually on piglets during the first 24 h of life. Measurements of IgG, IgA and IgM were performed on 3 samples of colostrum after 0, 12 and 24 h following the birth of the first piglet, then in the serum of the piglets, sampled at 4, 12 and 42 days of age. Then, we calculated the total amount of Ig intake during the first 24 h of life and an estimation of the Ig stores of each piglet on the basis of weight, blood volume, and hematocrit at different ages. Results showed a marked average difference in the birth weight in favour of mature piglets as well as an increased colostrum intake: 315 vs an average of 213 g for premature piglets. Considerable variations between sows were found in the initial level of colostral IgG, independently of the gestation length. Two thirds of the IgG intake by piglets occurred during the first 12 h. Total Immunoglobulin intake in the first day was respectively 15.8 g vs 25.1 g for premature or mature piglets. Total estimated Ig content in the serum of 4 day-old piglets was also lower for premature ones (2.55 vs 3.2 g/animal), representing 10 to 27% of the total amount of Igs ingested during the first day of life.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutritional importance of colostrum in the piglet.

Suckling of colostrum by piglets is very important in order to improve the survival rate. Colostrum provides maternal antibodies, energy and protein. Rearing piglets suckling an artificial milk of a similar chemical composition to that of sow's milk failed when the animals were housed in conventional conditions although numerous research workers succeeded in rearing 90% of animals delivered and fed in sterile conditions. Studies on the chemical analysis of colostrum showed a high dry matter content (30-40% higher than that of milk) in particular a high protein level (twice that of milk). The high proportion of globulins, i.e. 38% during farrowing, drops to 12% of the protein 4 days later; conversely the casein content rather low at birth doubles over the same period. Colostrum proteins are not used to proved energetic nutrients; some of them are absorbed without hydrolysis and have a special physiological rôle. The transmission of maternal immunity by gamma globulins is well known; lactotransferrin plays an important rôle as a transporter and a bacteriostatic factor. Enzymatic proteins such as lyzozyme govern the metabolism of glycoproteins. Hydrolyzed albumins, casein and proteose-peptone fraction provide the essential amino acids for de novo protein synthesis. The fat content is relatively low during the first 24 hours and increases threefold in the 4 days after farrowing. It provides the majority of the energy required by the young animal. A high proportion of some fatty acids, mostly oleic and linoleic acids, are used preferentially as sources of energy. Other components, including enzymes of the mammary cells, were found, but their particular rôle has not been explained. Colostrum contains in addition numerous vitamins (vitamins A and E) and some particular trace elements (iodine and selenium), and their transfer from the maternal diet to the young is particularity efficient by colostrum suckling. The nutritional rôle of those nutrients is important and their levels could affect the survival rate of the piglets. Hypotheses concerning the digestion and absorption of nutrients and antibodies are summarized, and finally, recommendations are made for further research and for the minimum amount of colostrum required by each piglet for survival and efficient postnatal growth to be assessed.