Effect of nipple drinker water flow rate and season on performance of lactating swine.

A cooperative study involving six experiment stations and 236 crossbred litters was conducted to determine the effect of nominal nipple drinker water flows of 700 mL/min and 70 mL/min (actual = 701 and 76 mL/min, respectively) during winter (November through February; 124 litters) and summer (June through August; 112 litters) seasons on performance of lactating sows and their litters. Within a season, sows were paired according to expected farrowing date and assigned at random to crates. Water flow rate treatments were assigned at random to sows within pairs. Sows were housed in farrowing crates from d 109 of gestation until either d 21 (two stations) or d 28 of lactation (four stations). Within 24 h after farrowing, litters were adjusted to contain 8 to 12 piglets. Sow feed intake (SFI) and litter weight (LW) were recorded weekly. Sow weights were recorded at d 109 of gestation, d 0, and d 21 of lactation. Sows lactating beyond 21 d were also weighed on d 28. Analysis of covariance was applied to sow weight change, average daily SFI, and LW data where litter size after crossfostering was the covariate. Average ambient temperature 30 cm above the floor at 0830 and 1600 was 24.6 +/- 0.15 degrees C and 29.4 +/- 0.14 degrees C, respectively, during summer and 20.7 +/-0.13 degrees C and 21.8 +/- 0.11 degrees C during winter trials. Restricted drinker water flow rate decreased SFI (P < 0.01; 4.59 vs. 3.94 kg/d, respectively, for 700 and 70 mL/min) and increased BW loss (P < 0.01; 0.56 vs 0.89 kg/d, respectively for 700 and 70 mL/min) but did not affect litter size (P > 0.87) or LW (P > 0.89) during the first 21 d of lactation. During d 22 to 28, the 70 mL/min flow decreased SFI (P < 0.01; 5.02 vs. 4.47 kg/d respectively, for 700 and 70 mL/min). Over the 21-d lactation period, the 70 mL/min treatment depressed (P < 0.01) SFI more during the winter (5.12 vs. 4.24 kg/d for 700 and 70 mL/ min, respectively) than during the summer (4.05 vs 3.65 kg/d for 700 and 70 mL/min, respectively). Season affected SFI (P < 0.01; 4.68 vs. 3.85 kg/d, respectively, for winter and summer), sow weight loss (P < 0.001; 0.46 vs 0.83 kg/d, respectively, for winter and summer), and LW at 21 d (P < 0.05; 52.8 vs. 49.6 kg, respectively, for winter and summer) but not (P > 0.96) the number of pigs per litter. Results of this study suggest that ample access to drinking water and controlling ambient temperature during summer months are essential for sow and litter performance.

Factors affecting the number of teats in pigs.

The factors that affect the number of teats in pigs are of interest for both biological and practical reasons. Previous work indicates that there is a genetic component, principally from the dam. The proportion of males in a litter appears to be related to the anogenital distance of the gilts in the litter, possibly as a result of the intrauterine position effect. The present study investigated whether litter size, litter sex ratio, anogenital distance, crown-rump length, distance from base of skull to base of tail, and the number of teats on the dam and boar affected the number of teats on gilts. Stepwise multiple regression on litter mean values (adjusted r2 = 0.178) indicated that two factors were significant: the number of teats on the dam (standard coefficient 0.311) and the proportion of males in the litter (standard coefficient -0.282). A greater number of teats on the dam and a lower proportion of males in the litter resulted in a greater number of teats on the gilt. When the analysis was run using individual gilts as the independent units (adjusted r2 = 0.073), the number of teats on the dam (standard coefficient 0.207), the proportion of males in the litter (standard coefficient -0.135), and the weaning weight of the gilt (standard coefficient 0.083) were all significant predictors of the number of teats. This evidence suggests that teat number in female pigs is related to the proportion of males in the litter.

Conception failure in swine: importance of the sex ratio of a female's birth litter and tests of other factors.

Failure of gilts and sows to conceive when they are mated is a potentially serious economic cost for swine producers. In Exp. 1, we determined that anogenital distance of newborn gilts is related to the proportion of males in the litter (P < .001). Gilts from litters with more males have larger anogenital distances (mean = 8.0 +/- .2 mm); those from litters with low proportions of males have smaller anogenital distances (mean = 5.7 +/- .1 mm). In Exp. 2, we examined the effect of birth litter sex ratio of sows and gilts on reproductive performance using a 13-yr database of breeding and litter data. Gilts that failed to become pregnant on the first breeding attempt came from litters with significantly higher proportions of males than gilts that successfully conceived on the first breeding attempt. Overall, female swine were significantly more likely to exhibit lower rates of successful breeding during their first four breeding attempts if they had been born in a male-biased litter. These results have implications for swine producers deciding which gilts to keep and which to market. Given the higher probability of reproductive problems for gilts from litters of 12 or more pigs with 67% or more males, these females should likely become market hogs. Sow's age, mode of insemination, and the number of insemination attempts at an estrus period, but not season, can affect successful breeding.

Pituitary and Leydig cell function in boars actively immunized against gonadotrophin-releasing hormone.

Crossbred boars were (a) immunized against GnRH conjugated to human serum globulin (200 micrograms GnRH-hSG) in Freund's adjuvant at 12 weeks of age and boosted at weeks 18 and 20 (N = 10), (b) served as controls and received hSG only in adjuvant (N = 10), or castrated at weaning (N = 10). At 24 weeks of age (immediately before slaughter), the boars were challenged with saline or pig LH (1 microgram/10 kg body weight). After slaughter, fresh testicular fragments were incubated with pig LH (0.05 and 0.2 ng/2 ml medium) to assess the effects of immunization on Leydig cell function. Pituitary contents of LH and FSH, and testicular LH receptor content were also measured. The results indicated that plasma LH and testosterone concentrations, pituitary LH content, testicular LH receptor content, testis and sex accessory organ weights were significantly reduced in GnRH-immunized boars compared to hSG-adjuvant controls. However, plasma and pituitary FSH content were not affected by high antibody titres generated against GnRH. The testicular testosterone response to exogenous LH in vivo and in vitro was significantly reduced (P less than 0.05) in GnRH-immunized boars. These results indicate that active immunization against GnRH impairs pituitary and Leydig cell functions in boars.

Changes in testicular morphology in boars actively immunized against gonadotropin hormone-releasing hormone.

Alterations in testicular morphology were studied in boars actively immunized against gonadotropin hormone releasing hormone (GnRH). Ten boars were divided equally into two experimental groups (five GnRH-immunized, and five controls). Antibody production was achieved by conjugating GnRH to human serum globulin (hSG). The GnRH-hSG conjugate was emulsified in complete Freund's adjuvant, and administered to boars at 12 weeks of age. Boars were given a booster in incomplete Freund's adjuvant on week 18 and 20. The presence of high antibody titers to GnRH caused luteinizing hormone and testosterone to decline to nondetectable levels. Morphometric examination showed a reduction in percentage volume in Leydig cells/unit testis, seminiferous tubule diameter and seminiferous epithelial height, and an increase in non-Leydig cell interstitial tissue in GnRH-immunized boars compared with controls. Histologic evaluation displayed severe damage of the seminiferous epithelium, absence of spermatids, incomplete cell associations, disruption of Sertoli cells, formation of multinucleated giant cells, and a striking reduction in size and cytoplasmic structures of Leydig cells in GnRH-immunized animals. These results demonstrate the potent inhibitory effects of GnRH immunoneutralization on the boar reproductive system.

Effect of active immunization against LHRH or LH in boars: reproductive consequences and performance traits.

Forty crossbred boars were equally divided into eight groups at birth. Four groups were immunized (200 micrograms/boar) at 12 wk of age against either luteinizing hormone-releasing hormone (LHRH) conjugated to human serum globulin (LHRH-hSG) in complete Freund's adjuvant (CFA), LHRH-hSG in muramyldipeptide adjuvant (PEP), procine luteinizing hormone (LH) conjugated to hSG (pLH-hSG) in CFA or ovine LH (oLH) in CFA. Equal doses of boosters were given in either PEP or incomplete Freund's adjuvant (IFA) at 16 and 18 wk of age. Two groups of boars were immunized with either hSG + CFA or hSG + PEP (adjuvant controls). Two groups were castrated either at the time of weaning (castrate weaning) or at 16 wk when immunized boars were given their first booster injections (castrate booster). All pigs were slaughtered at 24 wk of age. Serum levels of LH and testosterone (T), LHRH or LH antibody titers, as well as testicular and accessory sex gland weights and histology were determined. By wk 16, LHRH antibody titers began to rise in those boars immunized against LHRH-hSG. Luteinizing hormone-releasing hormone antibody titers on wk 18, 20 and 22 were greater than those at wk 16. By 22 wk of age, LHRH-hSG boars had non-detectable plasma LH and T and reduced weights of testes and acessory sex glands. Boars immunized against oLH did not respond to treatment, whereas pLH-hSG boars showed a reduction in serum T levels and accessory sex gland weights. Immunization had no effect on average daily gain, hot carcass weights or loin eye area.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum pesticide levels in patients with childhood colorectal carcinoma.

From September 1974 through November 1976, 13 adolescent patients with mucin-producing colorectal adenocarcinoma were treated at a Memphis, Tennessee, pediatric oncology center. Ten of these children were from rural areas of the Mississippi Delta, areas of high pesticide use. None of them had a family history of colorectal cancer, familial polyposis, or ulcerative colitis. Levels of pesticide residues, however, were not generally higher in blood samples from patients and their families than from controls.

Agar slush as a method to insure homogeneity of monocentric fungi in continuous culture.

Agar granules suspended in the growth medium reduce clumping, which permits the continuous culture of monocentric chytridiomycete fungi.

Organochlorine pesticide residues in human milk samples from women living in Northwest and Northeast Mississippi, 1973-75.

Organochlorine pesticide analyses were performed on human milk samples obtained from 34 women living in the Mississippi Delta, a high pesticide usage area, and from six women living in Starkville, Mississippi, a low pesticide usage area. Nine women collected samples before and after their babies had nursed so that fat levels and sigma DDT levels could be compared on whole milk and milk fat bases. sigma DDT values were independent of collection time if calculated on a milk fat basis, but not if calculated on a whole milk basis. Thus, the most consistent indicator of DDT residues were values calculated on a milk fat basis. Residue levels for p,p'-DDE, p,p'-DDT, and sigma DDT were significantly different (P less than 0.01) in samples from the two areas. Residues of o,p'-DDT, beta-BHC, and oxychlordane in milk samples from women living in the high pesticide usage area also were significantly different (P less than 0.05). A mean value of 19.17 ppm sigma DDT, found in the milk fat of samples from the high pesticide usage area, is the highest ever reported. Samples from the low pesticide usage area contained a mean level of 2.36 ppm sigma DDT.

DDT residues in air in the Mississippi delta, 1975.

In a previous publication the authors reported on 88 percent decrease in sigma DDT (DDT plus metabolities) in air between 1972 and 1974 in the Mississippi Delta. This period was the first two years after the use of DDT was banned in the United States. The present report shows an additional 36 percent decrease in sigma DDT levels in air between 1974 and 1975. Thus in the past three years sigma DDT in air has decreased by 92 percent, a much more rapid decrease than had been expected.

Insecticide exposure of mothers and newborns in a rural agricultural area.

Pregnant women in a rural agricultural area were found to have levels of residues of chlorinated hydrocarbon insecticides in their serum which were comparable to those found in occupationally exposed men. Cord blood of offspring also had significant residue levels. Residues were higher in blacks and in mothers living in rural areas where exposure was more intense. In newborns no signs or symptoms compatible with acute chlorinated hydrocarbon poisoning were found. Despite the lack of DDT use during most of the study period, over 90% of the mothers. 84% of the black newborns, and 45% of the white newborns demonstrated evidence of recent DDT exposure.