Effects of ram preexposure and ram breed on fertility of ewes in summer breeding

Suffolk x Rambouillet ewes were used in two consecutive years to test the ability of Dorset and Suffolk yearling rams to stimulate ovulation and estrus in early summer (late June and July) breeding. After spring weaning about June 1, ewes were randomly divided into three groups and for 2 wk either were isolated from rams or were preexposed to either yearling Dorset or Suffolk rams by penning of rams in proximity to ewes. Ewes then were rerandomized into two groups for joining with either yearling Dorset or Suffolk rams fitted with marking harnesses. Serum progesterone profiles and crayon marks were used as indicators of ovulation and estrus. Overall lambing rate was not different among preexposure treatments for the 2 yr. However, early lambing rate (in the first 14 d of lambing season) was significantly affected by preexposure group (24% for Dorset vs 9% for Suffolk and 10% for isolation), especially in the 2nd yr (31% for Dorset vs 8% for both Suffolk and isolation). Ewes preexposed to Dorsets also lambed 10 d earlier (P less than .05) than ewes preexposed to Suffolks in yr 2, but the groups did not differ in yr 1. Ewes exposed to Dorset rams for breeding had higher overall lambing rates than ewes bred to Suffolks (75% vs 54%), especially in the 1st yr (77% vs 48%). Lambs sired by Dorset rams were born 6 d earlier in yr 1 (P less than .05) but only 1 d earlier in yr 2. Data from both years indicate that Dorsets are superior to Suffolks in ability to sire lambs in fall lambing systems.     

Use of melengestrol acetate and gonadotropins to induce fertile estrus in seasonally anestrous ewes.

Ewes of three genotypes (Hampshire, n = 59; Rambouillet, n = 36; crossbred, n = 57) were used to determine the efficiency of melengestrol acetate (MGA) and(or) PG-600 (a combination of pregnant mare's serum gonadotropin and human chorionic gonadotropin) in inducing fertile estrus in seasonally anestrus ewes. Ewes were assigned randomly, within genotype, to treatments in a 2 x 2 factorial arrangement. Treatments were control, .125 mg of MGA given twice per day for 9 d (MGA), a single 5-mL injection of PG-600 (PG-600), and the combination of treatments MGA and PG-600 (MGA/PG-600). Feeding of MGA began on May 14, 1990, and ended on May 23. Injections of PG-600 were given immediately after the last feeding of MGA or vehicle on May 23. All ewes were exposed to fertile, brisket-painted rams on May 24 (d 0) for 40 d. Ewes were checked for estrus twice daily for 9 d. Laparoscopy was performed, to assess ovulation rate (OR), on d 6 for ewes that were not detected in estrus and on d 12 for ewes that exhibited estrus. Percentage of ewes mated was increased by MGA (P less than .001). Ovulation rate of ewes exposed to rams was increased by PG-600 (P less than .01) and this effect was enhanced by MGA (P less than .05), whereas MGA alone tended to decrease OR (P less than .10). Melengestrol acetate decreased the interval to lambing by 6.5 d (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Conception rates in early postpartum ewes bred naturally or by intrauterine insemination

Ewes were treated with a medroxyprogesterone acetate (MAP) sponge for 8 d followed, at sponge removal, with 500 IU pregnant mare serum gonadotropin (PMSG) at d 30, 40 or 50 (d 0 = lambing) to induce estrus. Dry and lactating ewes were divided into equal numbers at each postpartum day and bred at estrus. Conception rates and number of accessory sperm were determined by flushing the oviducts 3 d after mating and examining the recovered ova. There was no effect (P greater than .05) of lactational status on conception rates. Conception rates increased (P less than .05) from d 30 (10%) to d 40 (45%) and from d 40 to d 50 (80%). There were fewer (P less than .05) ova with accessory sperm (5/26) in d-30 ewes compared with d-40 (10/27) or d-50 (12/24) ewes. In Exp. 2, ewes were assigned to two groups after receiving PMSG on d 30: 1) mated naturally or 2) inseminated during laparotomy near the uterotubal junction (UTJ). Dry and lactating ewes were divided evenly within each of the two treatments. Oviducts were flushed and ova were examined for cleavage. The conception rate was 60% in ewes that were inseminated in the UTJ vs 10% in ewes mated to rams (P less than .05). Lactational status had no effect on results. In conclusion, conception rates in postpartum ewes treated with MAP sponge and PMSG increased from postpartum d 30 to d 50 with natural breeding, and d-30 conception rates were increased over natural mating by insemination into the uterine horn near the UTJ.     

Embryonic migration relative to maternal recognition of pregnancy in sheep

Twenty-five crossbred ewes were utilized to examine the timing of embryonic migration relative to maternal recognition of pregnancy. These ewes also were utilized to examine whether ovine embryos synthesized estradiol-17 beta in association with embryonic elongation and intrauterine migration. Embryos were flushed on d 11 through 15 from hemiovariectomized ewes. Recovery of embryos from the uterine horn contralateral to the remaining ovary indicated that migration had occurred. Ewes subsequently were returned with rams to determine their interestrous interval. Recovered embryos were classified morphologically, their length determined and individually incubated. Changes in estradiol within the medium were determined after a 6-h incubation. Embryo migration began on d 14 (P less than .05); on consecutive days from 11 through 15, 0, 0, 0, 60 and 100% of ewes examined, respectively, had an embryo in the contralateral horn. Extended estrous cycles (greater than 20 d) were observed in 0, 0, 40, 80 and 100% of ewes examined (P less than .05) following removal of embryos on d 11 through 15 of the cycle. Ovine embryos were longer (P less than .05) on d 14 (4.8 +/- 1.1 cm length, mean +/- SE) compared with d 13 (.2 +/- .1 cm) and increased further (P less than .05) on d 15 (7.8 +/- 1.1 cm). Incidence of intrauterine migration was correlated with embryonic length (r = .83; P less than .01) and estradiol synthesis (r = .77; P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of Finnish landrace crossbred ewes with Columbia, Rambouillet and Targhee ewes on western range

The objective of this study was to compare reproductive efficiency and wool production of 1/4 Finn crossbred ewes with straightbred Columbia, Rambouillet and Targhee ewes. In Phase I, white-faces ewes (WF; Columbia, Rambouillet and Targhee) were bred to either rams of their own breed or Finnish Landrace X Rambouillet rams (F X R) to produce 821 lambs from 563 lambings. Ewes bred to F X R had similar average litter size and individual lamb weights at birth, 60 d and weaning as those bred to WF. Lambs sired by F X R had 7% higher (P less than .01) lamb weaned per ewe lambing for ewes bred to F X R rams. For Phase II, approximately equal numbers of F X R-sired (1/4Fx) and WF-sired female lambs produced in Phase I each year were exposed to Suffolk rams at yearly intervals beginning at 7 mo of age. At 1 yr of age, 1/4Fx had higher fertility (P less than .01) than WF (37.7% vs 1.3%), resulting in 14.0 kg more lamb weaned per ewe exposed to breeding. Mature (ages 2 to 6 yr) 1/4Fx ewes had similar fertility to mature WF ewes, but litter size, number of lambs at 60 d and weaning was .36, .24 and .22 lambs higher (P less than .01), respectively, for mature 1/4Fx. Progeny of 1/4Fx were lighter at birth (P less than .01), but not different (P greater than .05) at 60 d and weaning than those of WF. Survival to 60 d unadjusted and adjusted for birth weight was 4.6% (P less than .05) and 7.6% (P less than .01) higher, respectively, for 1/4Fx progeny than for WF progeny.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ram influence on ovarian and sexual activity in anestrous ewes: effects of isolation of ewes from rams before joining and date of ram introduction.

A 2-yr experiment was conducted to determine whether isolation of ewes from rams is necessary to achieve a high response to the ram effect and whether ewes respond as well in May as in June. The experiment was conducted at two locations, with the same four treatments at each location. The four treatments differed with respect to ewe proximity to rams before mating (isolated vs adjacent) and date of joining with novel breeding rams (May 15 vs June 15). The proximity treatment at one location was changed in the 2nd yr; teaser rams were joined with the ewes instead of being adjacent to them. Overall, 86% of the eligible ewes were judged to have responded to the ram effect. A period of isolation before mating did not increase response compared with ewes that remained adjacent to, or in contact with, rams (86 vs 85%). Response was greater (P less than .05) in June and in the 2nd yr (P = .05). A physiological response, different from that generally described, was identified. Ewes ovulated approximately 8 d (8.0 +/- .19 d) after joining with breeding rams. The subsequent ovulation, accompanied by estrus, occurred approximately 15 d later (15.3 +/- .29 d). Eighty-five percent (87/102) of the ewes sampled responded in this manner. However, 82% (31/38) of a sample of these ewes had at least one morphologically normal corpus luteum when examined by laparoscopy 4 d after joining. It seems that these corpora lutea were not completely functional with respect to progesterone production. The ram effect can be achieved without prior isolation of ewes from rams.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of number of lambs suckled and supplemental protein source on lactating ewe performance

Effects of number of lambs suckled and supplemental protein source on ewe performance were determined. Lactation performance of ewes nursing twin or triplet lambs was compared in Exp. 1 and 2. In Exp. 1, ewes giving birth to and nursing triplets produced 21% (P less than .05) more milk/unit metabolic body weight, were 10% more efficient in the conversion of feed to milk and produced 26% (P less than .05) more kg of lamb/ewe on d 42 of lactation than did ewes giving birth to and nursing twins. In Exp. 2, lactation performance of ewes giving birth to triplets and rearing only two lambs was compared with performance of ewes giving birth to triplets and rearing three lambs. Ewes rearing three lambs produced 28% (P less than .08) more milk and were 26% (P less than .05) more efficient in converting feed to milk than were those rearing two lambs. This suggests that direct nursing stimulation of the mammary gland is responsible for the improvement in milk production observed when ewes nurse additional lambs. The efficacy of slowly degradable protein sources for improved lactation was studied in Exp. 3 and 4. When blood meal was fed to twin-rearing ewes at 3.30% of the diet (25% of total dietary protein), milk production was greater (3,176 vs. 2,506 g/d, P less than .05) and efficiency of milk production was greater (1.05 vs .79 g milk/g feed, P less than .05) than when ewes were fed supplemental soybean meal. Ewes in this experiment fed supplemental meat and bone meal also tended to produce more milk than those fed soybean meal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of cohabitation with white-faced ewes on estrous activity of Hampshire and Suffolk ewes exposed to rams in June

Two groups of 24 Hampshire and 26 Suffolk purebred ewes each were used to study effects of cohabitation with cyclic white-faced (WF) ewes on estrous activity in June. Ewes lambed in January, February and March and had been isolated from mature rams since the previous fall breeding. From June 1 to July 2, treated (T) ewes were exposed to vasectomized rams and to 65 WF ewes; control (C) ewes were exposed only to vasectomized rams. Ovulation was assessed with biweekly serum progesterone assays; crayon marks were used to detect estrus. Daily observations of ram behavior were conducted to assess sexual activity of rams joined with T and C ewes. Cohabitation with WF ewes increased (P less than .01) ovulation percentages from 46% in C (42% for Hampshires and 50% for Suffolks) to 76% in T ewes (79% for Hampshires and 73% for Suffolks). Mating percentage also was increased (P less than .05) by cohabitation with WF ewes from 14% for C ewes to 30% for T ewes. Rams with T + WF ewes spent more (P less than .05) time checking ewes for estrus than did rams with C ewes. Hence, cohabitation with cycling WF ewes increased ovulation and mating percentages. Many acyclic T ewes first ovulated after 10 or more days of teasing, possibly due to increased ram contact in the presence of WF ewes.     

Effects of plane of nutrition and phenobarbital during the pre-mating period on reproduction in ewes fed differentially during the summer and mated in the fall

An increased plane of nutrition of ewes before mating (flushing) has been associated with an increased number of lambs per ewe. The following study was done to investigate a possible mechanism for the flushing effect. During the summer, 98 Hampshire and Suffolk ewes grazed pastures with 50 of the ewes supplemented with .45 kg of corn grain X head-1 X d-1. For approximately 12 d before fall mating, each ewe received daily either .45 kg of a corn grain-soybean oil meal mixture, an oral dose of 1 g phenobarbital or no treatment. Liver biopsies were collected from 23 ewes, representing all treatment combinations, 3 d after initiation of pre-mating treatment for determination of concentration of hepatic mixed function oxidase enzymes (MFO). Summer supplementation vs no summer supplementation resulted in ewes with heavier (P less than .05) body weights near mating (75.6 vs 71.1 kg), higher (P less than .01) mating condition scores (3.2 vs 2.9), a greater (P less than .01) number of ovulations (1.99 vs 1.74), but little difference (P greater than .10) in number of lambs born per ewe lambing. Pre-mating treatment with phenobarbital or grain mix resulted in a greater number of ovulations (P less than .01, P less than .10, respectively) than no pre-mating treatment (2.14, 1.85, 1.60; respectively). Ewes given phenobarbital had more (P less than .10) lambs per ewe than ewes given no treatment (1.71 vs 1.40). Both phenobarbital and grain mix resulted in a significant increase in concentration of MFO compared with no treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Performance of Polypay, Coopworth, and crossbred ewes: II. Survival and cumulative lamb and wool production over 4 years.

Six ewe genotypes, generated by mating Coopworth (C), Polypay (P), and Suffolk (S) rams to P and Coopworth-type (Ct) ewes, were exposed to Hampshire rams for spring lambing from 1987 through 1990. Data from 1,013 exposures and 973 resultant lambings were used to analyze reproductive traits and cumulative ewe productivity over 4 yr. Ewe body and fleece weights were also analyzed. Ewes from S sires weaned the heaviest lambs and ewes from P sires weaned the largest number of lambs, resulting in similar total weight of lamb weaned per ewe mated. Coopworth-sired ewes weaned the least total weight of lamb per ewe mated. Ewes weaning twins produced 54% more total litter weight per ewe than those weaning singles. Annual ewe survival averaged 95%, ranging from 93% for S x P and C x P ewes to 97% for P x Ct and C x Ct ewes. When cumulative number and weight of lamb produced was assessed on the basis of all ewes starting the trial, P-sired ewes were highest, followed in order by daughters of S and C sires. Suffolk-sired ewes (67 kg) were 13% heavier than daughters of P rams and 19% heavier than daughters of C rams. Adjustment of lamb production for ewe metabolic body size resulted in C-sired ewes being more efficient than the heavier S-sired ewes. Coopworth-sired ewes produced 32% more wool than ewes sired by the other two breeds. Differences in wool production between ewes weaning one or two lambs were small.(ABSTRACT TRUNCATED AT 250 WORDS)     

The influence of pregnancy and source of supplemental protein on intake, digestive kinetics and amino acid absorption by ewes

Three experiments were conducted with ewes to determine the effects of pregnancy and(or) supplemental protein source on amino acid absorption and digestive criteria. In Exp. 1, four mated and five nonmated ewes fitted with abomasal and ileal cannulas were offered 272 g of cracked corn/d and ad libitum alfalfa hay (22% CP). Mated ewes absorbed greater quantities (P less than .10) and percentages (P less than .05) of amino acids presented to the abomasum than did nonmated ewes between d 121 and 124 of gestation. In Exp. 2, three nonmated ewes were used in a latin square design experiment to compare amino acid absorption when timothy hay (6% CP; 67% NDF) was offered alone or with supplements of corn plus either alfalfa hay (ALF) or soybean meal (SBM). Supplementation increased total, essential and nonessential amino acid flow to the abomasum and amino acid disappearance. In Exp. 3, 12 mated and 12 nonmated ewes were assigned to treatments in a 2 x 2 factorial arrangement to compare the effects of production status (gestation followed by lactation vs nonmated) and supplemented protein source (ALF vs SBM) on voluntary intake and digestive criteria. Ewes were pulse-dosed with Yb-marked NDF from hay on d 124 and 137 of gestation and d 26 of lactation. During lactation (d 7 to 28), dietary DM intakes were greater (P less than .05) by ewes consuming ALF compared with SBM and by lactating ewes compared with nonmated ewes. Flow rates were greater (P less than .05) from mated ewes throughout the experiment. It appears that pregnant ewes met their increased nutrient demands by increasing flow rates and by more efficient apparent absorption of amino acids.     

Effects of supplemental protein source and metabolizable energy intake on nutritional status in pregnant ewes.

Two experiments were conducted to evaluate effects of supplemental protein source and ME intake (Exp. 1) on ewe nutritional status during pregnancy. Forty-two mature Targhee ewes were allotted randomly in Exp. 1 to one of six treatments (n = 7) using a 2 x 3 factorial arrangement. Ewes were individually fed chopped barley straw and supplements containing either urea (U), soybean meal (SBM), or blood meal (BM) plus SBM during the 84-d experiment. Straw and supplement intakes were adjusted to meet either 80 or 100% of ME requirements. In Exp. 2, 30 pregnant Targhee ewes that were allotted randomly to one of three groups (n = 10) were individually fed protein supplements similar to those in Exp. 1 and had group access to long-stem barley straw. In Exp. 1, ewes fed BM + SBM gained more (P less than .05) weight, lost less (P less than .05) body condition, and had increased (P less than .05) wool fiber length compared with ewes fed U; SBM ewes were intermediate (P less than .05) in response. Ewes fed BW + SBM had increased (P less than .05) blood urea N and albumin concentrations compared with ewes fed U. Metabolizable energy intake did not affect (P greater than .05) ewe performance or serum metabolite concentrations. Ewes fed BM + SBM in Exp. 2 gained more (P less than .05) weight than ewes fed either SBM or U, and ewes fed SBM lost less weight (P less than .05) than ewes fed U.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of lasalocid and supplement level on productivity of gestating ewes grazing winter range

Two winter feeding trials (1985-86; 1986-87) were conducted to evaluate the productivity of gestating ewes fed lasalocid (L) and two supplement levels while grazing Montana winter range. Five hundred range ewes were randomized within age and breed each year and allotted to .15 or .23 kg hd-1.d-1 of a 20% CP supplement and either no L or L at 70 mg hd-1.d-1. Feed treatments began on 18 Dec. approximately 100 d before the first expected lambing date and continued for 84 d. Ewes fed .23 kg of supplement per day gained more (P less than .01) total weight (4.9 vs 4.0 kg) during the 84-d experiment and had higher (P less than .05) grease fleece weights (4.2 vs 4.0 kg) than those fed .15 kg of supplement. Lasalocid had no effect (P greater than .05) on ewe weight change or grease fleece weights. Supplement level had no effect (P greater than .05) on reproduction, lamb mortality and lamb performance. Ewes fed L had a greater (P less than .05) percentage of lambs born per ewe than those not fed L (120.7 vs 112.1%); lamb performance was similar (P greater than .05) between treatments. However, because a greater percentage of lambs were born per ewe starting the experiment, ewes fed L produced more (P less than .05) kilograms of weaned lamb than those not fed L (25.9 vs 23.4 kg). In conclusion, ewes fed L and grazing winter range weaned more kg of lamb than did controls because of an improved lambing percentage.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of prenatal androgenization on lamb performance, carcass composition and reproductive function

Two experiments were conducted in which pregnant crossbred ewes were randomly assigned to a control group or implanted with testosterone propionate/silastic implants between d 40 and d 60 of gestation. Implants contained approximately 2 g testosterone propionate and provided a constant delivery of 8.7 mg/d. Androgenized ewes (TE), born to implanted dams, had lower adjusted birth weights (P less than .05) than control ewes (CE) in both experiments. Treated rams (TR) also displayed lower birth weights than control rams (CR) in both experiments, but the difference was significant only in Exp. 2. Average daily gain was 16.4% more (P less than .05) for TE than for CE in Exp. 1. In Exp. 2, TE gained 9.6% faster (P less than .05) and had 14.6% (P less than .05) more weight per unit of feed consumed than CE. In both experiments, average daily gain and gain-to-feed ratio were similar for TR and CR. In Exp. 2, prenatal androgenization of ewes reduced (P less than .05) 12th rib fat thickness and decreased (P less than .05) percent kidney and pelvic fat. Yield grades of TE were lower than CE in both Exp. 1 (P less than .10) and Exp. 2 (P less than .05). From additional measurements taken in Exp. 2, liver weight per unit of carcass weight was greater (P less than .05), anogenital distance was greater (P less than .01) and test tube penetration into the vestibule was less (P less than .01) for TE than CE. The TE did not exhibit regular estrous cycles, while CE displayed recurring estrous cycles.     

Effect of progesterone supplementation on pregnancy and embryo survival in ewes

Two hundred eighteen ewes were used in experiments 1) to develop a progesterone supplementation regimen capable of sustaining serum concentrations of progesterone at about 2.0 ng/ml for a period of 50 d (Exp. 1) and 2) to determine the effects of progesterone supplementation (d 6 to 50 after mating) on pregnancy and embryo survival rates in mated ewes (Exp. 2). In ovariectomized ewes in Exp. 1, s.c. administration of four cylindrical (9.5 x 60 mm) silastic implants, containing 20% (1.1 g) progesterone by weight, sustained mean serum concentrations of progesterone of 1.9 +/- .07 ng/ml compared with 1.03 +/- .05 ng/ml in ewes bearing two implants. In Exp. 2 each ewe (n = 159) was mated to two fertile rams at a spontaneous estrus (d 0) during mid-breeding season. Mean ovulation rate, determined on a subgroup of 46 ewes, was 1.45 +/- .05. On d 6, ewes were assigned randomly to control (two implants containing no progesterone) or progesterone-treated (four implants similar to those used in Exp. 1) groups. From d 7 to 50 after mating, progesterone concentrations in serum were greater (P less than .001) in progesterone-treated (four implants similar to those used in Exp. 1) groups. From d 7 to 50 after mating, progesterone concentrations in serum were greater (P less than .001) in progesterone-treated (3.50 +/- .06) than in control (2.65 +/- .05) ewes. Pregnancy rates (86% and 83%) and calculated embryo survival rates (77% and 78%) were similar (P greater than .05) for the control and progesterone-treated groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

A comparison of six methods used for detecting pregnancy in sheep

The speed and accuracy of 4 ultrasonic devices (Scanopreg, Pregmatic 3, Medata external probe and Medata rectal probe) were compared with udder scoring and harnessed vasectomised rams as methods of pregnancy diagnosis in 177 ewes, 59 of which were non-pregnant. When using the Scanopreg in ewes of greater than 50 days gestation, accuracy in pregnant ewes averaged 98% and in non-pregnant ewes 87%. The Pregmatic 3 was 97% accurate in pregnant ewes after 50 days gestation and was 96% accurate in non-pregnant ewes. Ewes were examined at between 85 and 185 per hour using these devices. The Medata external probe was 99% accurate in pregnant ewes of greater than 110 days gestation but less accurate in early gestation. This instrument averaged 89% accuracy in non-pregnant ewes and an examination rate of 29 to 35 ewes per hour was achieved. The Medata rectal probe averaged 85% accuracy in pregnant ewes after 70 days gestation. Accuracy averaged 94% in non-pregnant ewes. Ewes were examined at between 35 and 59 per hour using this device. After 130 days gestation 84% of ewes had firm, obviously enlarge udders and another 14% had slight to moderate udder development. After 130 days gestation thick, clear udder secretions were expressed from 18% of ewes and thick, milky udder secretions were expressed from 8%. Harnessed vasectomised rams raddled one of 118 pregnant ewes (an accuracy in pregnant sheep of 99%) and raddled 53% of non pregnant ewes. It was concluded that the ultrasonic pregnancy testing devices have a commercial role, especially as aids to decision making.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of ammonium tetrathiomolybdate intake on tissue copper and molybdenum in pregnant ewes and lambs

Pregnant ewes (d 32 of gestation) were allocated to three treatments and given intraruminal controlled-release devices designed to deliver 0, 20 or 60 mg diammonium tetrathiomolybdate (TTM) per day. Ewes given 20 or 60 mg TTM/d also received an oral drench of 120 or 360 mg TTM twice weekly commencing on d 86 of gestation. Liver and kidney samples were taken from lambs 48 h after birth and from ewes on d 18 postpartum. Trichloroacetic acid soluble Cu, ceruloplasmin and superoxide dismutase activities in the plasma of ewes were decreased (P less than .05) by TTM. Liver Cu concentrations were decreased (P less than .05), but kidney Cu concentrations increased (P less than .05) by 16-fold in ewes given the higher dose of TTM. Liver and kidney Mo concentrations were elevated (P less than .05) 9- and 30-fold, respectively, in ewes given TTM. Plasma glucose concentrations in ewes were decreased (P less than .05) by the highest level of TTM treatment. Lambs of ewes given TTM had a fivefold increase (P less than .05) in liver Mo concentration, but kidney Mo concentration was not affected (P greater than .05) and liver Cu concentration was reduced (P less than .05). In ewes, Mo apparently caused Cu to be mobilized from the liver and a Cu and Mo complex accumulated in the kidney. Some Mo crossed the placenta, but only limited Mo accumulated in the fetal livers. When given to pregnant ewes, TTM reduced liver Cu levels in the lambs but did not affect the concentration of Cu in colostrum.     

Digesta kinetics, ruminal fermentation characteristics and serum metabolites of pregnant and lactating ewes fed chopped alfalfa hay

Eight ruminally cannulated ewes (four control and four bred; average BW = 85.7 kg), limit-fed alfalfa hay (1.86% BW), were used in two experiments to determine the effects of pregnancy and lactation on digestive function and serum metabolites. Seven-day sampling periods were used starting on d 102, 118 and 132 of gestation (Exp. 1) and d 14 and 32 of lactation (Exp. 2). Particulate (6.8 vs 4.9%/h; PPR) and fluid passage rates (13.9 vs 10.9%/h) were greater (P less than .05) and gastrointestinal mean retention time (28.9 vs 35.7 h) and fluid turnover time (FTT, 7.5 vs 9.5 h) were lesser (P less than .05) in pregnant than in nonpregnant ewes, respectively. Isobutyrate concentration was lower (P less than .05) in pregnant (1.7 mol/100 mol) than in nonpregnant (1.9 mol/100 mol) ewes. No differences (P greater than .10) were noted for any other ruminal fermentation measures between pregnant and nonpregnant ewes. In Exp. 2, no differences (P greater than .10) were noted in digesta kinetics or ruminal fermentation measures except for isobutyrate and isovalerate molar proportions and serum urea N (SUN) concentration. Isobutyrate, isovalerate and SUN concentrations (21.8 vs 26.1 mg/dl) were lower (P less than .05) in lactating ewes than in nonlactating ewes. Gastrointestinal fill (5.7 vs 7.7 g/kg BW) and FTT (9.3 vs 12.7 h) were lesser and DM digestion (66.7 vs 57.4%) was greater (P less than .05) in lactating than in nonlactating ewes. Data suggest that, during pregnancy, passage rate increases occur without affecting DM digestion and that, during lactation, PPR is not affected when ewes are limit-fed.     

Performance of Polypay, Coopworth, and crossbred ewes: I. Reproduction and lamb production.

Six ewe genotypes, generated by mating Coopworth (C), Polypay (P), and Suffolk (S) rams to Polypay and Coopworth-type (Ct) ewes, were exposed to Hampshire rams for spring lambing from 1986 through 1990. Data from 1,092 exposures and 1,044 resultant lambings were used to analyze reproductive traits and lamb growth rates. Overall conception rate averaged 95% and ranged from 93% for S x Ct ewes to 97% for P x Ct ewes. Mean litter size at birth averaged 1.63 and ranged from 1.45 for C x C ewes to 1.75 for S x P ewes. Ewes from P dams had higher mean litter size (P less than .01) than those from Ct dams (1.73 vs 1.54), but differences between sire breeds were not significant. Incidence of lambing assistance was similar for ewes producing single or multiple lambs. Lamb birth weight influenced the level of assistance rendered to single-bearing but not to multiple-bearing ewes. Lambing assistance was not related to lamb survival, probably because the high surveillance level minimized trauma before assistance was rendered. Incidence of required assistance declined over subsequent parities. Lamb birth weights were affected by ewe genotype and increased with increasing ewe age. Survival of single-born lambs averaged 94% and was not affected by dam genotype. Survival of twins averaged 85%, ranging from 79% for lambs from S x Ct ewes to 89% for lambs from P x P ewes. Suffolk-sired ewes produced the heaviest mean birth and weaning weights for both singles and twins. Coopworth-sired ewes weaned heavier single lambs but lighter twins than P-sired ewes.     

Effects of vitamin E and selenium injections on reproduction and preweaning lamb survival in ewes consuming diets marginally deficient in selenium

Medium wool ewes were injected with vitamin E and(or) Se over a 2-yr period to evaluate the influence of these treatments on reproduction. Ewes were divided randomly into four groups, consisting of a control, plus groups receiving monthly sc injections of either 272 iu vitamin E, 4 mg Se or 272 IU vitamin E plus 4 mg Se during pregnancy. Selenium administration increased (P less than .05) ewe blood Se concentrations, but had no effect (P greater than .10) on fertility (number of ewes lambing of ewes bred), prolificacy (number of lambs born/ewe lambing) or lamb sex ratio. Preweaning survival of lambs was increased (P less than .05) by ewe treatments with either Se or vitamin E and thus, treated ewes weaned approximately 20% more lambs/ewe mated than did control ewes.