Complete restriction of all food intake of sows for 2, 3, or 4 days after weaning tended to increase the interval from weaning to estrus in sows. It did not, however, have a detrimental or beneficial effect on other measures of reproductive performance. These results would indicate this management practice of fasting to stimulate estrual activity is not valid

Allrich, R. D.

Johnson, John N.

Tilton, J. E.

NDSU Libraries Institutional Repository

RETURN TO CYCLIC ACTIVITY OF SOWS AFTER FASTING R. D. AUrich, J. E. Tilton, John N. Johnson and Ron Zimprich Complete restriction of a\l food intake of sows for 2, 3, or 4 days after weaning tended to increase the interval from weaning to estrus in sows. It did not, however, have a detrimental or beneficial effect on other measures of re­productive performance. These results would indicate this management prac­tice of fasting to stimulate estrual activity is not valid. Recently, questions have been raised as to the value of imposing a fasting period upon weaned sows. This management practice has been infrequently employed by producers throughout the pper Midwest. It was thought that fasting would hasten the "drying-off" proc­e ss of the weaned sow, enabling her to return to estrual activity sooner. Lactating sows show no cyclic activity; however, upon weaning, estrus (sexual receptivity) will oc ur in four to ten davs. F w studies have examined the effects of fasting at w~aning on swine reproduction. The practice of fasting sows after weaning has been investigated by Brooks and Cole (1973), Using a 2 x 2 factorial design , feed intake in the last week of lactation and feed intake 24 hours after weaning were examined for their effect on return to estrus and number of piglets born. These researchers examined e ither high (5.4 kg) feed intake or low (2.3 kg) feed intake during the last week of a six-week lactation and fasted the sows for 0 or 1 day after weaning. There were no sib'Ilificant effects of treatment on days to return to estrus. However, a trend for increased tim to return was noted in fasted animals. Number of pigl ts born did not differ Significantly. Their findings sugg st that the practice of fasting does not af­fect post-weaning reproductive performance. After a 42-day lactation period, Brooks and Cole (1972) fasted sows for 24 hours foIIowmg weaning, then allotted the sows onto one of three feeding levels (1. 8, 2.7 or 3.6 kg feeclJday) until the day of mating. The number and we ight of pigs born was not significantly affected by treatment. There was a tendency for litter size to increas with each increase in feeding level (9.4, 10.4 and 11.6 pigs born for 1.8, 2.7 and 3.6 kg/feed/day). In a survey of non-infec tious infertility, ~acLean (1969) stated that complete starvation and water depriva­tion for 24 hours on the day of weanin was the most effec:tivt' method of stimulating early estrus onse t as compared to a 24-hour fast with water available and a 24-hour fast in combination with a dose of Epsom salt. MacLean conjectured that complete starvation and wate r de privation stimulates the "drying-off" process, . enabling the sow to re turn to estrus in a shorter in terval. A research proj ct was initiated at the North Dakota Agricultural Experi rn nt Station at Fargo to determine the influence of fasting on sow reproduction. The exper­iment reported he rein was designed to determine the effect of a post-weaning fast on the sow's ability to return to estrual activity . PROCEDURE At weaning, Duroc sows were randomly assigned to a fasting interval of either 0, 2, 3 or 4 days. This fasting period was initiated at weaning. Sows were weaned onto an open-lot dirt pen that contained a straw-bedded shed for shelter. A maximum of 20 sows were penned to­gether. 'When not fasting, sows received 2.3 kg feed (16% crude protein) daily . The sows were checked for estrual activity twice daily, 0800 and 2000 hours, and were bred by Duroc boars 12 and 24 hours after the onset of estrus. During the winter months, the evening check was performed at 1600 hours because of darkness. Records of weaning date and day of first estrus were kept for each sow. A total of 99 sows contributed data in this experiment. RESULTS AND DISCUSSION Table 1 contains the data obtained from this experi­ment. Fasting (2, 3, or 4 days) caused an increase in the interval from weaning to the first estrus. The control group (0 day bstJ required an average of 5.2 days to return to estrus after weaning, compared to 6.4, 6.9 and 5. 8 days for the 2, 3 sand 4 day fasted groups, respec­tively . Upon statistical analysis these differences were not significant. No udder problems were encountered in any of the treatment groups. The results obtained in this experiment suggest that the management practice of fasting de lays the ons t of estrus aft~ r weaning. Hog producers lI sually want weaned sows to return to estrus in as short a time as possible. This allows for prompt rcbr eding and another pregnancy to be IInderway. In this way the farrowing inte rval (time be tween two consecutive parturitions) ­would be at a minimum , allowing f()r maximum pro­ductivity for each sow. If for some reason , such as lack of boar pow r, the producer wishes to deby the onset of the postweaning estrus, fasting for three days would delay estrus 101- p ­proximately one day, as illustrated by th p re sent re­sults, compared to a non-fasted animal. Th is re"ponse depends on many factors , probably the most signifIcant 33 being lactation length. As lactation length increases, the interval from weaning to estrus decreases. The mean lactation length used in the present experiment was 27 days. Data are now being processed to determine what eflects fasting has on ovulation rate, embryonic mortality and number of pigs born alive at the subsequent farrow­ing. AUrich and Tilton (1978), using preliminary data, have indicated that fasting may be detrimental to the aforementioned factors. SUMMARY Ninety-nine Duroc sows were utilized in an experi­ment to determine the effect of a postweaning fast on the weaned sow's ability to return to cyclic activity. Any degree of fasting (2, 3 or 4 days) increased the interval from weaning to first estrus when compared to the con­trol animals (0 day fast). The control group re(luired an average of 5.2 days to return to estrus after weaning, compared to 6.4, 6.9 and 5.8 days for the 2,3 and 4 day fasted groups, respectively. These differences were not statistically significant. From present results, it appears that fasting sows at weaning should not be recommended due to its effect of delaying the return to estrus. Further research needs to be conducted on the feeding level of the sow during the interval from weaning to es trus. It may be that an in­creased feeding level in this interval would be the most beneficial. TABLE 1. DAYS TO RETURN TO ESTRUS AFTER WEANING Fasting Period Number of Days to Return (Days) Sows (Mean) 0 28 5.2 2 22 6.4 3 21 6.9 4 28 5.8 References Cited 1 	 Allrich, R. D. and J. E. Tilton. 1978. Improving Postpartum Re­production in the Pig. NDSU Liw'stock Res arch Day Report. 2. Brooks, P. H. and D. J. A. Cole. [972. The Effects of Nutrition Between Weaning and Remating on the Reproductive Perfor­mance of Primiparous Sows. Anim. Prod . 15:259. 3 . Brooks, P. H. and D. J. A. Cole. 1973. The Effect of Feed Pallern in Lactation and Fasting Following Weaning on Reproductive Phenomena in the Sow. Vet. Record 93:276. 4. 	 MacLean, C. W. 1969. Observations on Non-Infectious Infertility in Sows. Vet. Record 85:675. NONRESIDENT WATERFOWL HUNTING LEASES Jay A. Leitch and Donald M. Elliott* One alternative available to hunters faced with dwindling hunting oppor­tunities is to lease hunting rights from landowners . In 1976, 18 percent of nonresident waterfowl hunters in North Dakota paid for the right to hunt on private land at an average cost of $26 each. Most Americans have considered hunting a basic right. Present day conditions often interfere with the freedom of hunters to pursue f!;ame as they did in bygone years. Increased population , dWindling wildlife habitat, and pressure by f!;roups opposed to killing wild animals have all brought pressure to bear on the freedom of hunters. One of several alternatives available to hunters *Leitch is research associate and Elliott is graduate research assistant, Department of Agricultural Econom­ics. is to lease hunting rights from landowners. In North Dakota this generally implies leasing from farmers who own wetlands or wildlife habitat. There are several advantages to leasi ng hunting rights . One advantage to the hunter is that it assures him of a place to hunt. He will not have to spend hunting time trying to get permission to hunt from landowners. Also, the lessee, by virtue of leasing a selected piece of land, expects to have a fairly good chance of hunting success, better than at a place where he CQuid get per­mission to hunt without paying. Because of this , Leasing 34 

Return to Cyclic Activity of Sows After Fasting

Abstract

Similar works

Full text

Available Versions

NDSU Libraries Institutional Repository