9. Composition of sow colostrum and milk
Components of milk include proteins, lipids, carbohydrates, minerals, vitamins, and cells. The contents of these components are affected by a variety of factors, with stage of lactation having the most dramatic influence on composition. Mammary secretions from the sow during the initial 24 h after parturition are generally higher in concentrations of immunoglobulins, some microminerals and vitamins, and hormones and growth factors, and lower in concentrations of lactose, when compared with mature milk. Fat concentration in sow milk is transiently increased during the period from day 2 to day 4 of lactation. The composition of milk after day 7 to day 10 is relatively stable for the remainder of lactation. Diet can affect some milk components, including concentrations of fat, fat soluble vitamins and some minerals, as well as proportions of specific fatty acids. Genetics, parity, colostrum and milk yield, and ambient temperature have also been found to affect component composition of colostrum and milk. This chapter summarizes some of the literature available on sow colostrum and milk composition. Benchmark averages of component concentrations based on values reported in the literature are also provided.