COMPARATIVE STUDY OF COLOSTRUM AND MILK COMPOSITION OF SEVEN BREEDS OF SWINE
Colostrum and milk samples taken at 1, 14, 28, and 35 days after farrowing from 31 sows of seven breeds (Yorkshire, Landrace, Lacombe, Duroc, Hampshire, Berkshire, and Large Black) were chemically analyzed to study the effects of breed and stage of lactation on composition. Breed was a significant source of variation for fat, sodium, and magnesium percentages of milk, and potassium percentage of the colostrum. Significant breed differences were also found in energy and ash, total solids, and phosphorus percentages. Yorkshire, Hampshire, and Lacombe were generally higher and Berkshire and Large Black lower in milk constituents than the other breeds. Significant changes in total solids, protein, ash, calcium, and phosphorus percentages were observed with the advance in lactation. The overall means for the different determinations of milk corrected for the effects of breed and stage of lactation were: specific gravity, 39 Quevenne/15.6 C; energy, 1.11 kcal/g; ash %, 1.04; total solids %, 19.0; fat %, 6.3; protein %, 5.4; calcium %, 0.20; sodium %, 0.04; potassium %, 0.10; magnesium %, 0.02; and phosphorus %, 0.17.