Mammary gland growth in the lactating sow

The short lactation period of the modern sow is critical for determining th e success of piglet survival and growth. Increases in milk production durin g early lactation may result from increases in. secretory cell numbers, enh ancement of functional differentiation of cells, or both mechanisms. The po rcine mammary gland undergoes substantial growth during lactation. Mammary tissue wet weight can increase by more than 50% and total mammary gland DNA by 100% during a 21-day lactation. Postpartum mammary growth parallels the increase in milk production observed during lactation. Mammary growth duri ng lactation is affected by litter size, dietary intake, and gland location , as well as by a number of other factors. A primary factor influencing pos tpartum mammary growth is removal of milk from the gland. A suckled mammary gland, in combination with the piglet that suckles it, form an interdepend ent growing unit. Mammary glands which are underdeveloped at parturition ca n still grow rapidly in response to suckling. The sow's mammary gland has t remendous potential for growth during early lactation. Approaches for enhan cing mammary gland growth during early lactation offer substantial potentia l for enhancing milk yield and piglet growth. (C) 2001 Elsevier Science B.V . All rights reserved.