TY - JOUR TI - Effect of nutritional status, age at weaning and room temperature on growth and systemic immune response of weanling pigs. AU - Crenshaw, T.D. AU - Cook, M.E. AU - Odle, J. AU - Martin, R.E. T2 - Journal of animal science DA - 1986/// PY - 1986/// VL - 63 IS - 6 SP - 1845-1853 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0023015344&partnerID=MN8TOARS ER - TY - JOUR TI - Prenatal and postnatal correlated responses in maternal traits of mice assessed by crossfostering AU - Eisen, E. J. AU - Bandy, T. R. T2 - Genetics, Selection, Evolution DA - 1986/// PY - 1986/// DO - 10.1186/1297-9686-18-2-145 VL - 18 IS - 2 SP - 145 ER - TY - JOUR TI - EFFECTS OF ZERANOL AND TRENBOLONE ACETATE ON TESTIS FUNCTION, LIVE WEIGHT-GAIN AND CARCASS TRAITS OF BULLS AU - SILCOX, RW AU - KEETON, JT AU - JOHNSON, BH T2 - JOURNAL OF ANIMAL SCIENCE AB - The ability of zeranol and trenbolone acetate (trenbolone) to alter testis function, weight gain and carcass traits of young bulls was studied. In Exp. 1, the effects of age at initial zeranol implantation was determined. After a 235-d experimental period, sequential implantation (56-d intervals) beginning at 100 or 150 d of age had reduced testis growth (P<.01), sperm production (P<.01) and serum testosterone concentration in response to gonadotropin releasing hormone (GnRH; P<.01). The 200-d age group was partially suppressed, while the 250-d age group was not affected. Body weights were similar to controls in all groups. In Exp. 2, bulls previously implanted with zeranol at 175 and 231 d of age received single implants of zeranol, trenbolone or trenbolone plus zeranol at approximately 300 d of age. At slaughter (135 d later), body weight and carcass characteristics in all treatments were similar to controls. However, trenbolone reduced sperm production (P<.05), zeranol reduced sperm production and testes weight (P<.05), but trenbolone plus zeranol was similar to controls. Mean testosterone response to GnRH was suppressed in all implant groups on d 65 (P<.01), but only in trenbolone or trenbolone plus zeranol groups on d 112 (P<.05). Results indicate that zeranol suppresses spermatogenesis and testosterone production if implanted before approximately 200 d of age. Reduction of endogenous testosterone without alteration of weight gain or carcass characteristics may be of benefit if behavioral or masculinity traits of bulls are altered. Also, it appears that no benefit is derived from implanting bulls with both trenbolone and zeranol. DA - 1986/8// PY - 1986/8// DO - 10.2527/jas1986.632358x VL - 63 IS - 2 SP - 358-368 SN - 1525-3163 ER - TY - JOUR TI - GROWTH, DEVELOPMENT AND BODY-COMPOSITION IN 3 GENETIC STOCKS OF SWINE AU - TESS, MW AU - DICKERSON, GE AU - NIENABER, JA AU - FERRELL, CL T2 - JOURNAL OF ANIMAL SCIENCE AB - Differences in growth, chemical body composition and visceral organ development were evaluated in three genetic stocks: Beltsville Highfat (HF) and Lowfat (LF) Duroc-Yorkshire composites and a Hampshire × Large White cross (CX). Ten sets of littermate barrows were used from each stock. One pig from each set was slaughtered at 10, 17 and 24 wk of age. After slaughter, each pig was dissected into three fractions: carcass, head and feet, viscera and blood. Backfat was measured at three locations and visceral organs were weighed separately. Each fraction was frozen, ground, sampled and analyzed in duplicate for protein, fat, water and ash. The CX pigs were heaviest at all ages and contained the most fat-free mass (FFM). The HF pigs were smallest and contained the most fat, while LF pigs tended to be intermediate. The LF pigs deposited a greater proportion of weight in head and feet and a greater proportion of total FFM in the carcass than HF and CX pigs. Estimated allometric growth coefficients for non-fat chemical components relative to empty body weight (EBWT) were lower for HF than LF and CX, which were similar. Coefficients for fat were similar among stocks yet intercepts differed widely. Relative to total FFM, water increased at a faster rate and ash a slower rate in CX pigs compared to HF and LF. Growth coefficients were calculated for internal organs relative to EBWT. Coefficients for organs of the digestive tract were not different among stocks. However, significant differences among stocks were found for heart, lung, spleen and liver that were not explained by differences in body composition. DA - 1986/4// PY - 1986/4// DO - 10.2527/jas1986.624968x VL - 62 IS - 4 SP - 968-979 SN - 0021-8812 ER - TY - JOUR TI - DETERMINANTS OF ESTROUS BEHAVIOR IN LACTATING HOLSTEIN COWS AU - BRITT, JH AU - SCOTT, RG AU - ARMSTRONG, JD AU - WHITACRE, MD T2 - JOURNAL OF DAIRY SCIENCE AB - The objective was to determine factors that affect the expression of estrus. Thirteen lactating Holstein cows were ovariectomized about 4 to 6 wk postpartum and then challenged repeatedly with progesterone and estradiol benzoate to induce estrus six times during the postpartum period. Each challenge included 5 d when the cow was primed with progesterone through insertion of a progesterone-impregnated, foam rubber pessary. Estradiol benzoate (1 mg) was injected intramuscularly 36 h after removal of the pessary. Groups of two to three cows each began the experiment at 3-mo intervals to avoid confounding treated simultaneously. Observations for estrous behavior were at 8-h intervals following each challenge. A minimum of three sexually active cows were always observed together to avoid differences in estrous behavior caused by having too few sexually active animals in the group. Observations for estrous behavior were at 8-h intervals following each challenge. During each observation, cows were observed for 30 min on dirt and for 30 min on concrete. Standing behavior was not influenced by postpartum interval, season of year, or milk yield. Mounting behavior increased from the first to the sixth postpartum challenge, but it was not affected by season of year or milk yield. Duration of estrus, mounting activity, and standing activity were greater on dirt than on concrete. These results indicate that the surface on which cows were observed had a profound effect on sexual behavior; however, postpartum interval, season of year, and milk yield were of minor importance. DA - 1986/8// PY - 1986/8// DO - 10.3168/jds.S0022-0302(86)80653-1 VL - 69 IS - 8 SP - 2195-2202 SN - 0022-0302 ER - TY - JOUR TI - Seasonal differences in function of the hypothalamic-hypophysial-ovarian axis in weaned primiparous sows AU - Armstrong, J. D. AU - Britt, J. H. AU - Cox, N. M. T2 - Journal of Reproduction & Fertility AB - Summary. Primiparous sows were fed to appetite during lactations that occurred during winter or summer, and 11·4 ± 0·4 pigs per litter were weaned at 23·5 ± 0·1 days of age. Sows were slaughtered at 0 or 72 h after weaning or blood samples were collected until 24 h after onset of oestrus. Sows that lactated during summer consumed less food and lost more (P < 0·05) weight, heartgirth and backfat than those that lactated during winter. Weaning-to-oestrus interval was greater (P < 0·05) in summer (224 ± 25 h) than in winter (93 ± 13 h). Content of GnRH in the hypothalamus and concentrations of LH in the anterior pituitary and serum were lower (P < 0·05) after weaning in summer than winter. The numbers of visible ovarian follicles < 5 mm in diameter at weaning were lower (P < 0·05) in summer than in winter. In contrast to LH, FSH concentration in serum was higher (P < 0·10) in summer than winter, but FSH values in the anterior pituitary were lower (P < 0·05) in summer than in winter. Post-weaning patterns of secretion of oestradiol and follicular development differed between winter and summer. For example, in some sows weaned during the summer, transient surges of oestradiol occurred repeatedly during 0 to 280 h after weaning without provoking surges of LH. These results indicate that the period of post-weaning anoestrus in summer is prolonged because of altered activity of the hypothalamic– pituitary axis, possibly because of changes in sensitivity to the feedback of oestradiol. Lower feed intake during lactations that occur during summer may predispose the endocrine system to the aberrations. DA - 1986/// PY - 1986/// DO - 10.1530/jrf.0.0780011 VL - 78 IS - 1 SP - 11 ER - TY - JOUR TI - Recombinant DNA, gene transfer and the future of animal agriculture AU - Petters, R. M. T2 - Journal of Animal Science DA - 1986/// PY - 1986/// VL - 62 IS - 6 SP - 1759 ER - TY - JOUR TI - CLEARANCE RATE OF LUTEINIZING-HORMONE AND FOLLICLE-STIMULATING-HORMONE FROM PERIPHERAL-CIRCULATION IN THE PIG AU - ESBENSHADE, KL AU - VOGEL, MJ AU - TRAYWICK, GB T2 - JOURNAL OF ANIMAL SCIENCE AB - Passive immunization of chronically ovariectomized gilts against gonadotropin releasing hormone (GnRH) resulted in an abrupt cessation of pulsatile secretion of luteinizing hormone (LH) accompanied by clearance from serum with a mean half-life of 30.9 ± 2.3 (mean + SE) and 918 ± 200 min for the first and second compartment, respectively. Serum follicle stimulating hormone (FSH) was unaffected immediately by passive immunization against GnRH and declined slowly with a half-life of 4.9 ± . 7 d. After LH and FSH had declined to basal levels in passively immunized gilts, injection of a bolus of LH and FSH resulted in peak values within 5 min and depletion curves with half-lives for the first compartment of 28.0 ±1.3 and 36.4 ± 2.6 min and for the second compartment of 679 ± 98 and 1,230 ± 54 min, for LH and FSH respectively. These results show that the half-life of LH is similar following immunoneutralization of GnRH or administration of a bolus of LH in immunized gilts and a difference in clearance rates of LH and FSH after initial passive immunization. These results suggest that secretion of FSH in the ovariectomized gilt is controlled by factors in addition to hypothalamic GnRH. DA - 1986/6// PY - 1986/6// DO - 10.2527/jas1986.6261649x VL - 62 IS - 6 SP - 1649-1653 SN - 0021-8812 ER - TY - JOUR TI - BODY CONDITION OF SOWS ACROSS PARITIES AND RELATIONSHIP TO REPRODUCTIVE-PERFORMANCE AU - ESBENSHADE, KL AU - BRITT, JH AU - ARMSTRONG, JD AU - TOELLE, VD AU - STANISLAW, CM T2 - JOURNAL OF ANIMAL SCIENCE AB - Weight, heartgirth, backfat and body condition of sows was monitored in a commercial, farrow-to-finish unit during 1 yr. Measurements were obtained during the third, ninth and fifteenth week of gestation and the day after weaning. Litter performance and rebreeding rate also were recorded. Body weight and heartgirth increased (P less than .01) over parities because gestational gains were larger than lactational losses. Backfat tended to be lower in later parities. Body weight, heartgirth and backfat, but not condition score, declined from weaning to the third week of the subsequent gestation in both first and second litter sows. Correlations among measures of body condition were low (less than .45), except the overall correlation between body weight and heartgirth. Number of pigs born alive increased and interval to estrus decreased in later parities. There were no significant relationships between changes in body condition and rebreeding performance of sows. These results suggest that changes in body condition typically observed in sows housed in commercial production units may be too subtle to have an effect on reproductive performance. DA - 1986/5// PY - 1986/5// DO - 10.2527/jas1986.6251187x VL - 62 IS - 5 SP - 1187-1193 SN - 0021-8812 ER -