Submitted to: Swine Day Report
Publication Type: Experiment Station
Publication Acceptance Date: 8/28/1997
Publication Date: N/A
Interpretive Summary: Traditionally, piglets are weaned at 21 to 28 days of age. However, the use of early weaning (before 17 days of age) is becoming increasingly common in the swine industry. Early weaning can improve the health status of piglets resulting in improved pig growth. The objectives of this study were to determine the impact of weaning age and dietary protein level on sow performance. Forty-two sows were fed either a high protein or low protein diet during lactation. Their piglets were either early weaned (EW, 8-17 days of age) or conventionally weaned (CW, 20-31 days of age). Sows were then slaughtered on either day 4,6, or 8 postweaning and various tissues were collected for examination. Early weaning reduced sow weight loss associated with lactation. Accordingly, the piglets weights were also lower when early weaned. Examination of the sows reproductive tracts revealed that EW sows had not recovered from the previous pregnancy as much has CW sows. The brain levels of beta-endorphin and CRF, two hormones associated with stress in pigs, did not differ between the groups of sows suggesting that weaning time did not impact these stress-related pathways. In summary, early weaning appears to have minimal negative biological effects on sows. However, following EW, sows require additional time for recovery of the reproductive tract whereas CW sows are typically ready to breed immediately following weaning. The potential loss in reproductive efficiency of the early weaned sow should be weighed against the benefits in pig output when choosing a weaning age.
Technical Abstract: The use of early weaning (less than 17 day lactation) to develop high health status pigs is becoming increasingly common in the swine industry. Early weaning provides health status benefits that result in improved pig growth performance. The objectives of this study were to determine the impact of weaning age and lactation dietary crude protein level on sow physiology and performance. Forty-two first parity sows were fed either a high protein (HP, 21.5%) or low protein (LP,14.4%) diet during lactation. Sows were either early weaned (EW,8-17 days) or conventionally weaned (CW,20-31 days). Sows were slaughtered on either day 4,6 or 8 postweaning and various tissues were recovered for examination. Early weaning reduced sow lactation weight loss, back fat loss, and litter weaning weight (P<0.05). Uterine weights of CW sows decreased at a greater rate and to a lower weight by day 8 postweaning than EW sows (P<0.02). The concentration nof beta-endorphin and CRF in the hypothalami of EW and CW sows did not differ suggesting that early weaning did not impact these stress-related pathways. Increased dietary crude protein during lactation increased the total number of ovarian follicles and early weaning tended to reduce total follicles by approximately 2. The potential loss in reproductive efficiency of the early weaned sow should be weighed against the benefits in pig output when choosing a weaning age.