RESUMEN

After parturition (Day 0), 31 mature spring-lambing, fine-wool ewes were randomly allotted to one of six groups. Treatments were lambs suckled (one or two) and ovine growth hormone (oGH; 0, 5 or 10 mg). Growth hormone was administered subcutaneously daily from Days 6 to 25. Milk characteristics were determined on Day 26. Ewes were observed for estrus beginning on Day 27. Serum insulin did not differ (P > 0.10) between suckling intensity before or after oGH treatment on Days 6, 15 or 25. Likewise, no difference (P > 0.10) in serum insulin was detected among ewes receiving 0, 5 or 10 mg oGH. Ewes suckling twins had higher (P < 0.05) serum growth hormone on Day 6 (before beginning oGH treatment) than ewes suckling single lambs. In ewes receiving 0, 5 and 10 mg oGH, serum growth hormone differed (P < 0.01) in a linear fashion 1 h after treatment was initiated on Day 6 and continued through Hour 6. Serum growth hormone on Days 15 and 25 differed among groups both before and after oGH was administered (P < 0.01). Suckling intensity did not affect (P > 0.10) milk or milk protein and fat yields; however, oGH increased (linear, P < 0.05) fat but did not affect milk or protein yields. Interval from parturition to estrus did not differ (P > 0.20) in ewes suckling single or twin offspring. Likewise, no differences (P > 0.20) in interval length were noted in ewes receiving 0, 5 or 10 mg oGH. Suckling intensity and oGH administration for 20 d had little effect on postpartum interval or milk characteristics during the first 30 d after lambing in fine-wool ewes.

RESUMEN

One month before a fall breeding season, 30 6-mo-old fine-wool ewe lambs were allotted to one of three treatment groups consisting of either 0, 2.5 or 5 mg ovine growth hormone (oGH) daily for 10 d and then, on alternate days, for an additional 20 d. Five ewes from each treatment group were bled at hourly intervals for 8 h on Days 0 (first day of treatment), 9, 19 and 29. Milk yield and composition were examined on Day 21 post partum. Neither feed intake nor ewe weights differed (P > 0.20) among treatments. Serum insulin did not differ (P > 0.20) among treatments before or during the 5 h following treatment on Day 0 or 29; however, 6, 7 and 8 h after oGH administration, a linear, dose-dependent increase (P < 0.10) in serum insulin was noted. On Day 9, serum insulin differed linearly (P < 0.10) before and after treatment. On Day 19, serum insulin differed (P < 0.10) among the groups 2, 3, 6, 7 and 8 h following oGH treatment. One hour after treatment on Day 0, serum GH increased linearly (P < 0.01) among groups. Serum GH continued to rise 3 h after treatment and remained elevated through Hour 8 in ewes receiving oGH. Serum GH was increased (P < 0.01) before and after oGH administration on Days 9, 19 and 29 in GH-treated ewes. Percentage of ewes that cycled during treatment or breeding as determined by serum progesterone was similar (P > 0.20) among groups. Pregnancy rates did not differ (P > 0.20) in ewe lambs receiving 0 (70%), 2.5 (80%) and 5 (60%) mg oGH. No differences were detected (P > 0.40) in milk yield or composition among treatments. In fine-wool ewe lambs treated with 2.5 or 5 mg of exogenous oGH for 30 d before breeding, neither reproductive performance nor subsequent milk production were enhanced; however, these treatments increased serum GH and insulin.

RESUMEN

After parturition, 10 mature spring-lambing fine-wool ewes producing twins were allotted to one of two treatments. Five ewes received sterile saline (i.v.) twice daily on Days 12 to 15 post partum (PP) while 5 ewes were treated similarly except each injection contained 500 mug somatostatin (SRIF). Jugular blood samples were collected at 15-min intervals for 1 h before to 3 h after morning treatment on Days 12 and 15 PP. Animals were observed twice daily for signs of estrus using vasectomized rams beginning on Day 31 PP and continuing until ewes returned to estrus. Interval from parturition to estrus (mean +/- SEM) was similar (P > 0.40) in ewes receiving SRIF (119 +/- 6.2 d) and in control ewes (113 +/- 6.2 d). Ewes receiving 500 mug SRIF had lower (P < 0.10) serum insulin during the first 45 min after treatment on Day 12 PP; however, on Day 15 PP, serum insulin did not differ (P > 0.40) between treatment groups. Serum growth hormone (GH) did not differ (P > 0.40) between treatment groups 1 h before treatment on Day 12 PP; however, ewes treated with SRIF had lower (P < 0.05) GH levels before treatment on Day 15 PP than control ewes (4.4 and 9.9 +/- 1.5 ng/ml, respectively). After administration of SRIF, serum GH was higher (P < 0.05) in SRIF-treated ewes than in controls (8.2 and 5.3 +/- 2.7 ng/ml, respectively) on Day 12 PP but no differences (P > 0.80) were noted between treatment groups on Day 15 PP. These data indicate that 500 mug SRIF given twice daily from Days 12 to 15 PP neither lowered serum GH nor influenced return to estrus in lactating fine-wool ewes.

RESUMEN

To determine the influence of protein supplementation on intake and fermentation of low-quality hay, six ruminal- and cecal-cannulated Rambouillet ewes (avg wt 43.6 kg) in a crossover design were given ad libitum access to prairie hay with or without 80 g of cottonseed meal (CSM) X head-1 X d-1. Voluntary hay intake was measured the last 7 d of each 18-d period. Ruminal, cecal and blood samples were collected at 0, 1 (except cecal), 3, 6, 9, 12, 15, 18, 21 and 24 h post-supplementation on d 14 of each period to measure fluid dilution rate, fermentation characteristics and serum concentrations of insulin and growth hormone. An intraruminal dose of Yb-labeled hay, followed by fecal sampling on d 15 through 18, was used to measure particulate passage rate. Voluntary intake of prairie hay was increased (P less than .04) from 23.7 to 28.3 g/kg of body weight by CSM supplementation. Particulate passage rate constants did not differ (P greater than .15) between supplemented (3.76%/h) and control (3.72%/h) ewes, and total mean retention time was not altered (P greater than .15) by CSM supplementation. Ruminal retention time of particulates did not differ (P greater than .15) between treatments; however, intestinal transit time was faster (P less than .03; 18.1 vs 22.6 h) in supplemented than in control ewes. Estimated gastrointestinal dry matter fill was greater (P less than .05; 14.3 vs 12.9 g/kg body weight) in supplemented ewes. Ruminal fluid volume did not differ (P greater than .15) between treatments; however, supplemented ewes tended to have faster fluid dilution rates (P less than .14) and fluid outflow rates (P less than .11) than control ewes. Cecal fluid volume, dilution rate and outflow rate did not differ (P greater than .15) between groups. Ruminal and cecal pH and total volatile fatty acids were similar between treatments. Similarly, cottonseed meal supplementation did not affect (P greater than .15) ruminal or cecal ammonia concentrations. Molar proportions of ruminal and cecal individual fatty acids were not affected (P greater than .15) by CSM supplementation. Feeding cottonseed meal increased (P less than .05) serum insulin, decreased (P less than .07) serum growth hormone and increased (P less than .06) serum free fatty acids, but did not influence (P greater than .15) either serum urea N or glucose concentrations. Cottonseed meal supplementation in ewes fed prairie hay caused increased hay intake but had minimal effects on ruminal and cecal fermentation.

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RESUMEN

In Exp. 1, 45 fine-wool ewes received (sc) either 0, 50 or 100 mg epostane (3-beta-hydroxysteroid dehydrogenase inhibitor) to examine effects on return to estrus and conception rates. Treatments were imposed on d 10 of an estrous cycle (estrus = d 0) and jugular blood samples were collected once daily on d 8 and 9, twice daily on d 10 through 13 and once daily from d 14 until first post-treatment estrus or d 20 (15 ewes/treatment). Intensive samples were obtained hourly for 6 h after treatment (d 10; five ewes/treatment). Serum progesterone (P4) before treatment was similar among groups; but by 2 h after treatment, epostane-treated ewes had lower (P less than .10) values than controls. By 6 h post-treatment, serum P4 in ewes receiving 50 (1.0 ng/ml) and 100 (.9 ng/ml) mg epostane was well below control values (3.2 ng/ml). By 7 d after treatment, 93.3% of ewes treated with 50 mg epostane had recycled compared with 66.7 and 33.3% of those receiving 100 and 0 mg, respectively (P less than .10). Similarly, 93.3, 53.3 and 26.7% of ewes receiving 50, 100 or 0 mg epostane, respectively, lambed to breeding within 7 d of treatment (P less than .05). Overall conception rates during a 34-d breeding season were similar among groups. Preweaning performance of offspring did not differ among maternal treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

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