Date of this Version
Milk was collected separately by machine from four to six glands on nine Yorkshire and Berkshire sows 2 or 3 days after farrowing and at weekly intervals throughout 6 weeks of lactation. Milk yield was measured following intramuscular injection of oxytocin, and the percent of ash, dry matter, fat and protein in the milk from each gland was determined. The average milk yield per gland, following a 1-hour period during which the pigs had been removed from the sow reached a peak of 74.6 gm. 3 weeks after farrowing. The ash content was 0.79% 2 or 3 days after farrowing, declined to 0.71% 1 week after farrowing and gradually increased to 0.96% 6 weeks after farrowing. The average dry matter content was 21.36% 2 or 3 days after farrowing, then declined to 19.52% 2 weeks after farrowing and increased to 20.55% at 6 weeks. The average fat content steadily declined from 7.83% 2 or 3 days after farrowing to 6.07% at 6 weeks. The average protein content was 5.97% at 2 or 3 days after farrowing, then declined to 5.26% at 2 weeks and gradually increased to 5.82% at 6 weeks. A highly significant difference (P < .01) among glands within sows was noted in fat content. No statistically significant differences were found in milk yield or in percents of ash, dry matter or protein within sows. Highly significant differences (P<.01) were found among sows in milk yield 2 or 3 days after farrowing and at each weekly interval thereafter. Highly significant differences among sows (P<.01) were noted in ash content 2 or 3 days and 1, 2, 3 and 6 weeks after farrowing, in dry matter content 2 or 3 days and 1, 2 and 3 weeks after farrowing, in fat content 1, 2, 3, 5 and 6 weeks after farrowing and in protein content, 1, 2, 3 and 6 weeks after farrowing. Significant differences among sows (P<.05) were also noted for dry matter content at 4 weeks and for fat and protein content at 5 weeks after farrowing. The data on within sow variation indicate that representative samples for ash, dry matter or protein content but not for fat can be obtained from a single gland.