@article{simpson_wesen_anderson_armstrong_harvey_1995, title={Subclinical mastitis and milk production in primiparous Simmental cows}, volume={73}, DOI={10.2527/1995.7361552x}, abstractNote={The prevalence of subclinical mastitis in beef cows was investigated and its relationship with milk production and 205-d adjusted calf weaning weights (ADJWW) determined. Primiparous Simmental cows (n = 25) were milked six times at approximately 30-d intervals. Before each milking, milk samples were aseptically collected from each quarter for bacteriological analyses. After recording milk weights, samples were obtained for determination of somatic cell counts (SCC), butterfat (BF), and protein (PRO). Somatic cell counts were transformed to Dairy Herd Improvement Association linear scores for statistical analyses. Cows were retrospectively assigned to one of two groups based on their SCC linear score being either less than (LOSCC) or more than (HISCC) 4.5, which corresponded to a SCC of 292 x 10(3) cells/mL. Milk samples from 32% (8/25) of the cows and 18% (18/100) of the quarters were culture-positive for bacteria (Staphylococcus aureus, Streptococcus dysgalactiae, Streptococcus species, Actinomyces pyogenes, and[or] coagulase-negative Staphylococcus) at one or more times. Milk production was higher in LOSCC than in HISCC cows (6.3 +/- .2 vs 5.4 +/- .3 kg/24 h; P = .004). Mean SCC linear score tended to be negatively correlated with mean milk production over the entire study (r = -.36; P = .08). Adjusted weaning weights were similar between calves suckling LOSCC and HISCC cows (243 +/- 5 vs 236 +/- 10 kg; P = .57). In summary, milk SCC concentrations in primiparous Simmental cows were highly variable. Higher SCC concentrations were associated with lower milk production in cows.}, number={6}, journal={Journal of Animal Science}, author={Simpson, R. B. and Wesen, D. P. and Anderson, K. L. and Armstrong, J. D. and Harvey, R. W.}, year={1995}, pages={1552} }
 @article{simpson_armstrong_harvey_1992, title={EFFECT OF PREPARTUM ADMINISTRATION OF GROWTH HORMONE-RELEASING FACTOR ON SOMATOTROPIN, INSULIN-LIKE GROWTH FACTOR-I, MILK-PRODUCTION, AND POSTPARTUM RETURN TO OVARIAN ACTIVITY IN PRIMIPAROUS BEEF HEIFERS}, volume={70}, ISSN={["1525-3163"]}, DOI={10.2527/1992.7051478x}, abstractNote={Forty-one primiparous beef heifers were used over 2 yr to evaluate the effect of prepartum administration of a growth hormone-releasing factor analog (GRF-A) or growth hormone-releasing factor (GRF(1-29)-NH2) on somatotropin (ST), insulin-like growth factor I (IGF-I), milk production, heifer BW, and postpartum (PP) return to ovarian activity. Beginning on d -11 +/- 1 from parturition, heifers were administered (s.c.) GRF-A ([desNH2-Tyr1,D-Ala2,Ala15]GRF(1-29)-NH2, 2.5 micrograms/kg; Yr 1) or GRF(1-29)-NH2 (12.5 micrograms/kg; Yr 2) (GRF; n = 17) or vehicle (CON; n = 24) for seven consecutive days. Blood samples were collected at 20-min intervals from -60 to 300 min from the first and fourth injections. Samples were also collected at 20-min intervals for 6 h on d 25 and 69 +/- 1 PP. Area under the curve of ST (nanograms.minute-1.milliliter-1) was greater (P less than .01) in GRF than in CON heifers (9,671 +/- 677 vs 2,611 +/- 237). Increases in ST after GRF-A or GRF(1-29)-NH2 were similar. On d 25 +/- 1 PP, frequency of ST release (pulses per 6 h) was greater (P less than .01) in CON (3.3 +/- .2) than in GRF (2.1 +/- .2) heifers. Milk production was similar (P greater than .1) for the two treatments. Heifer BW loss from d -16 to 81 after parturition was greater (P less than .01) in GRF (88 +/- 5) than in CON (68 +/- 5) heifers. Postpartum return to ovarian activity (progesterone greater than 1 ng/mL for two consecutive weeks) was delayed (P less than .05) in GRF (97 +/- 14) vs CON (71 +/- 8) heifers. After accounting for variation due to treatment and year, a negative (P less than .02) correlation (r = -.39) was detected between concentrations of IGF-I during the first 30 d PP and PP interval to ovarian activity. These results indicate that prepartum administration of GRF altered the release pattern of ST after parturition and was associated with greater PP BW loss and delayed PP return to ovarian activity in heifers.}, number={5}, journal={JOURNAL OF ANIMAL SCIENCE}, author={SIMPSON, RB and ARMSTRONG, JD and HARVEY, RW}, year={1992}, month={May}, pages={1478–1487} }
 @article{simpson_armstrong_harvey_miller_heimer_campbell_1991, title={EFFECT OF ACTIVE IMMUNIZATION AGAINST GROWTH HORMONE-RELEASING FACTOR ON GROWTH AND ONSET OF PUBERTY IN BEEF HEIFERS}, volume={69}, ISSN={["0021-8812"]}, DOI={10.2527/1991.69124914x}, abstractNote={Angus and Charolais heifers (195 +/- 7 kg) were actively immunized against growth hormone-releasing factor (GRF) to evaluate the effect on concentrations of somatotropin (ST), insulin-like growth factor I (IGF-I), insulin (INS), growth, and onset of puberty. Primary immunizations were given at 184 +/- 7 d of age (d 0 of experiment) by injecting (s.c.) 1.5 mg of GRF-(1-29)-Gly-Gly-Cys-NH2 conjugated to 1.5 mg of human serum albumin (GRFi, n = 22) or 1.5 mg of human serum albumin (HSAi, n = 21). Booster immunizations of .5 mg of antigen were given on d 62, 92, 153, and 251. Antibody binding (percentage at 1:2,000 dilution) to [125I]GRF on d 69 was greater (P less than .01) in GRFi (53.7 +/- 4.5) than in HSAi (10.1 +/- .6) heifers. Serum concentration (ng/ml) and frequency (peaks/5 h) of ST release, respectively, on d 78 were lower (P less than .01) in GRFi than in HSAi heifers (3.3 +/- .1 vs 5.6 +/- .2 and .9 +/- .3 vs 2.3 +/- .2). Serum IGF-I (ng/ml) was lower (P less than .01) in GRFi than in HSAi heifers on d 69 (41 +/- 5 vs 112 +/- 4). Serum INS (microU/ml) on d 78 was lower (P less than .05) in GRFi (2.2 +/- .1) than in HSAi (3.8 +/- .2) heifers. Feed intake, ADG, and feed efficiency were lower (P less than .05) in GRFi than in HSAi heifers. Hip height was lower (P less than .01) and fat thickness was greater (P less than .05) in GRFi than in HSAi heifers by d 132 and 167, respectively. Percentage of heifers attaining puberty (progesterone greater than 1 ng/ml for two consecutive weeks) by d 209 and 379 (12.9 and 18.5 mo of age), respectively, was lower (P less than .05) in GRFi (40.9 and 45.5) than in HSAi (81.0 and 100). In conclusion, growing heifers were successively immunized against GRF. Active immunization against GRF resulted in decreased serum concentration of ST, IGF-I, and INS. In addition, GRF immunization led to lowered feed intake, ADG, and feed efficiency, increased fat depth, and delayed onset of puberty in heifers. We propose that ST and IGF-I are important metabolic mediators involved in the initiation of puberty in heifers.}, number={12}, journal={JOURNAL OF ANIMAL SCIENCE}, author={SIMPSON, RB and ARMSTRONG, JD and HARVEY, RW and MILLER, DC and HEIMER, EP and CAMPBELL, RM}, year={1991}, month={Dec}, pages={4914–4924} }