Nutritional and immunological importance of colostrum for the new-born pig

The nutritional and immunological importance of colostrum for the survival and development of the neonatal pig are reviewed. The pig is born with low body energy stores and devoid of serum immunoglobulins. Colostrum provides the piglet with both energy and maternal antibodies but its fat and protein composition is very variable. Colostrum is very digestible, and both colostral energy and nitrogen (N) are retained with a very high efficiency. Colostrum production by the sow assessed from the weight gain of the litter from birth to 24 h of age is very variable (from 1900 to 5300 g). There is no clear effect of litter size or parity, suggesting that colostrum production is a characteristic of the sow. Within a litter, colostrum consumption by the individual piglets varies considerably. It is independent of birth order, but related positively to birth weight and negatively to litter size. Other factors influencing colostrum consumption, including cold stress, premature birth and birth hypoxia, are discussed. Because of the epitheliochorial nature of the porcine placenta, the new-born piglet must acquire maternal immunoglobulin G (IgG) from ingested colostrum for passive immune protection until the immune system of the piglet becomes fully developed. Colostrum IgG concentrations in milk vary widely between individual sows both in initial concentration and in the rate at which concentrations decline during the first 24 h of life. The piglet can only absorb intact IgG prior to gut closure, which occurs in the first 24 h of life and is induced by intakes of colostrum which are insufficient to maintain piglet live-weight. As a result, the amounts of intact IgG absorbed by the piglet vary widely. The effects of colostrum consumption on neonatal survival are discussed. Consumption of colostrum in amounts sufficient to meet the energy requirement of the piglet is a major determinant for survival. Since most neonatal losses occur in the first 2 days of life, before acquisition of a maternal IgG for immune protection becomes important for survival, piglet serum IgG concentration does not correlate well with early survival but is important in later resistance to disease challenge. It is concluded that colostrum production is a good marker for the maternal quality of the sow. Future research should focus on the ability of the sow to produce more colostrum and on the possible delayed effects of passive immunisation on the health and performance of piglet at weaning and later in life.