Dennis N. Marple

Endocrine changes in sows exposed to elevated ambient temperature during lactation

Seven sows were placed into one of two environmental chambers at 22 C, 5 d prior to farrowing. On day 9 of lactation, one chamber was changed to 30 C (n = 4) and the other remained at 22 C (n = 3). On days 24 and 25, blood samples were collected every 15 min for 9 hr and 7 hr, respectively. On day 24, thyrotropin releasing hormone (TRH) and gonadotropin releasing hormone (GnRH) were injected iv at hour 8. On day 25 naloxone (NAL) was administered iv at hour 4 followed 2 hr later by iv injection of TRH and GnRH. Milk yield and litter weights were similar but backfat thickness (BF) was greater in 22 C sows (P less than .05) compared to 30 C sows. Luteinizing hormone (LH) pulse frequency was greater (P less than .003) and LH pulse amplitude was less (P less than .03) in 22 C sows. LH concentrations after GnRH were similar on day 24 but on day 25, LH concentrations after GnRH were greater (P less than .05) for 30 C sows. Prolactin (PRL) concentrations were similar on days 24 and 25 for both groups. However, PRL response to TRH was greater (P less than .05) on both days 24 and 25 in 30 C sows. Growth hormone (GH) concentrations, and the GH response to TRH, were greater (P less than .0001) in 30 C sows. Cortisol concentrations, and the response to NAL, were less (P less than .03) in 30 C sows. NAL failed to alter LH secretion but decreased (P less than .05) PRL secretion in both groups of sows. However, GH response to NAL was greater (P less than .05) in 30 C sows. Therefore, sows exposed to elevated ambient temperature during lactation exhibited altered endocrine function.

Effects of Electrical Stimulation and Kidney-Pelvic Fat Removal Before Chilling on Microbial Quality of Beef Tenderloins1

Twenty-four steers (435-567 kg) were used to study the effects of electrical stimulation (50 V for 120 s) and of kidney-pelvic fat removal before chilling (3-4°C) on microbial populations of beef tenderloins on days 1, 4 and 7 post-mortem. Kidney-pelvic fat was stripped from one side of each carcass; the other side remained intact for later fat removal. On each respective chill-day, kidney-pelvic fat was aseptically removed from intact sides, tenderloins were swabbed at two anatomically referenced locations (3rd and 5th lumbar vertebra) and microbial load was determined. The statistical model for data analysis included the effects of electrical stimulation, chill-day, animal within chill-day X stimulation, fat removal, location, and all main effect interactions. Removal of kidney-pelvic fat before chilling resulted in a significantly higher bacterial load on the surface of exposed tenderloins after 24 h of chill. Electrical stimulation produced significantly lower bacterial counts for fat-intact surfaces on chill-day 7 and for fat-removed surfaces on chill-day 4. Kidney-pelvic fat removal allowed for significantly higher bacterial counts on the tail portion of tenderloins (3rd lumbar vertebra) for surfaces from non-stimulated carcasses than the butt portion (5th lumbar vertebra). Mean bacterial counts from electrically stimulated carcasses at the fifth and third lumbar vertebra locations did not differ (P>.10) between fat treatments.

Adenohypophyseal receptors for LHRH, pituitary content of gonadotropins and plasma concentrations of LH in cyclic, pregnant and postpartum beef cows.

Adenohypophyseal concentrations of LHRH receptors, pituitary content of LH and FSH, and plasma concentrations of LH were determined in thirty Hereford, Angus or Hereford-Angus heifers that were randomly assigned by breed and weight to five periods including day 3 of the estrous cycle (CY), pregnant day 120 (P120), 200 (P200), 275 (P275), or day 2 postpartum (PP). Jugular blood samples were collected at 10-min intervals for 8 hr from all cows. Within 2 hr after completion of blood sampling, animals were slaughtered and the pituitary gland frozen at -196 C. LH pulse frequency/8 hr was reduced (P less than .05) during gestation (.5, .2, and 1.5 +/- .5/8 hr, for P120, P200, and P275, respectively) and PP (.5 +/- .5/8 hr) compared to CY (7.8 +/- .5/8 hr). Frequency of LH pulses/8 hr was not different (P greater than .1) among P120, P200 or PP periods but was different (P less than .05) between P200 and P275. There were no differences in LH pulse height (P greater than .1) among periods; however, pulse amplitude was greatest (P less than .05) at P120 (1.3 +/- .2 ng/ml) and lowest between P200 and PP (.6 to .8 +/- .2 ng/ml). Baseline concentrations of plasma LH did not differ (P greater than .1) among P and PP periods (.3 +/- .1 ng/ml), but were lower (P less than .05) than in CY animals (.7 +/- .1 ng/ml). Concentration of adenohypophyseal LHRH receptors was approximately two-fold greater (P less than .05) at P120 (25.85 +/- 2.2 fmol/mg) than at all other periods (9.5 to 14.9 +/- 2.2 fmol/mg).(ABSTRACT TRUNCATED AT 250 WORDS)