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Reproductive performance of Suffolk and Suffolk-cross ewes and ewe lambs exposed to vasectomized rams before breeding.

Multiparous Suffolk and Suffolk-cross ewes were randomly allotted to treatments within breed and year to measure effects of ram exposure, during transition from anestrus to breeding activity, on reproductive performance. Treatments were: 1) ewes joined with two mature vasectomized Rambouillet rams for 15 d before breeding (DC), 2) ewes maintained across a net wire fence from two vasectomized rams for 15 d before breeding (FC) and 3) ewes maintained approximately 400 m away from rams (NC). At the end of the 15 d, all ewes were placed in one pasture and mated to three fertile Suffolk rams during a 34-d breeding season. A total of 96 Suffolk and 177 Suffolk-cross ewes was utilized during the 3-yr experiment. A greater (P less than .05) prebreeding ovulation percentage was observed in DC and FC than in NC ewes. Mating and lambing occurred approximately 6 d earlier for DC or FC ewes than for NC ewes. A similarly designed experiment was conducted using Suffolk and Suffolk-cross ewe lambs allotted to treatments within breed and year to measure effects of ram exposure during the natural breeding season, but prior to breeding. Treatment differences were not detected (P greater than .05) for date of first observed estrus, date of lambing, percentage of ewes lambing in the first 17 d of the lambing season, number of lambs born per ewe lamb exposed or number of lambs born per ewe lamb giving birth.

Anestrus↗

Influence of dietary protein during the pre-breeder period on subsequent reproductive performance of large white turkeys. 3. The effects of semen volume and frequency of insemination on fertility and hatchability.

Large White turkey breeders of a commercial variety were used to determine the effects of pre-breeder dietary protein, frequency of insemination, and semen volume on subsequent reproductive performance. Treatments included female dietary protein levels of 10, 12, 14, and 17% fed from 12 to 32 weeks of age and 10, 12, an 14% protein from 20 to 32 weeks of age; male dietary protein levels of 12 and 17% fed from 12 to 56 weeks of age; and artificial insemination (AI) treatments of a) .025 ml of semen at weekly intervals, b) .025 ml of semen at biweekly intervals, and c) .05 ml of semen at biweekly intervals in a factorial arrangement of treatments. Male dietary treatment had no significant effect on fertility or hatchability of fertile eggs. Female pre-breeder protein levels also had no significant effect on fertility but resulted in lower hatchability of fertile eggs during the latter part of the production period when females were fed either the 10 or 12% protein pre-breeder diets. Weekly inseminations with .025 ml of semen resulted in the highest average level of fertility during the production year (90%), followed by biweekly insemination with .05 ml (87%) and .025 ml (85%) of semen, respectively. Hatchability of fertile eggs was significantly higher for hens receiving .05 ml of semen biweekly than for the other two AI treatments during the latter half of the production year only. However, weekly inseminations caused a significant decline (6.7 eggs/hen) in egg production when compared to hens inseminated at biweekly intervals. The average number of fertile eggs was greatest for females inseminated with .05 ml semen biweekly (54.3) compared to those inseminated with .025 ml of semen biweekly (53.0) or .025 ml of semen weekly (50.2).

Animal Nutritional Physiological Phenomena↗

Effect of feeding time on the reproductive performance of Japanese quail (Coturnix coturnix japonica).

Several feeding regimens are applied to improve performance of fertile egg production during times of heat stress. During a period of heat stress (34 to 36 degrees C), two feeding periods were used to measure the impact of feeding time on reproductive performance of Japanese quail (Coturnix cotunix japonica) between 44 and 60 wk of age. Each feeding time treatment had 25 individually caged male and female pairs. Quail were fed ad libitum between 0600 to 1400 or 1400 to 2200 h daily. Results indicated that feeding between 0600 to 1400 h reduced BW, fertility, hatchability, egg production, and egg specific gravity when compared with the effects of feeding between 1400 to 2200 h. Feeding time had no effect on total embryonic mortality, egg weight, or the period between subsequent ovipositions. The different feeding times affected the distribution curve of oviposition over time. An instrument designed to record oviposition time is described. Results showed that selection of the time of day for application of an 8-h restricted feeding regimen affected BW, fertility, hatchability, egg production, egg specific gravity, and oviposition time in Japanese quail.

Animals↗

[Nickel--an essential trace element. 3. Effect of nickel deficiency on reproductive performance in female animals].

A total of 26 Ni-deficient (less than 100 ppm Ni in the ration) breeding goats and their 30 kids and 24 corresponding control goats with 37 kids were used to investigate, over 6 experimental years, the influence of Ni-deficiency on the reproductive performance until weaning. Following the same arrangement, 7 and 6 mini sows, respectively, and their piglets (71 and 67) were studied. The following statistically secured results were obtained. Ni-deficiency resulted in reduced pregnancy rates (after one insemination) in animals that had revealed clear estrus symptoms. This caused delayed pregnancies and birth of offspring. The conception and abortion rates, the number of offspring and the sex ratio were not influenced significantly by Ni-deficiency. Intra-uterine Ni-deficiency reduced the birth weights and caused lower weight gains during the suckling period. Its influence proved stronger in the kids as compared to the mini piglets. Ni-deficiency caused the mortality of the offspring during the suckling period to increase significantly. The losses in the Ni-deficient kids and mini piglets were by 41 and 51%, respectively, higher than in the corresponding control animals.

Abortion, Veterinary↗

Reproductive performance of postpartum beef cows after short-term calf separation and dietary energy and protein supplementation.

Beef cows (n = 294) calving between November and April in six states were used to evaluate the effects of postpartum diet and calf separation on body weight, body condition score (BCS), reproductive performance, and weaning weight of calves. In each state, half of the 48 cows that calved during 60 d were group fed an additional 4.5 kg of a 20% crude protein supplement daily for 28 d starting an average of 30 d post partum (flush). Calves were separated from half of the flush and half of the nonflush cows for 48 h at 14 and 28 d after the beginning of flush. Progesterone was quantified in plasma samples obtained weekly during a 56-d breeding period to assess ovarian luteal activity. The breeding period started at the first calf separation. BCS ranged from 3.3 to 5.6 among states (on a scale of 1 to 9) at the start of the flush but was similar for treatments within a state. There was a state x flush (P < 0.008) effect on body weight at the end of the flush period. Weaning weights were influenced by state x separation x flush (P < 0.06) and were greatest for flush nonseparated calves in five of six states. There were state x flush (P < 0.08) and separation (P < 0.04) effects on ovarian luteal activity at the start of the breeding period. Flush and separation tended to increase ovarian luteal activity. During the breeding period, ovarian luteal activity was influenced only by state but there was a state x separation x flush effect (P < 0.001) on the number of weeks post partum to onset of ovarian luteal activity. Conception rate and days postpartum to conception were not influenced by either separation or flush but were affected by state (P < 0.001). These data indicate that flushing may increase weaning weights of calves and calf separation may hasten the onset of postpartum ovarian luteal activity, but conception rate and days postpartum to conception for cows in thin to moderate body condition were not influenced by the calf separation or flushing treatments.

Journal Article↗

Synchronization of estrus and reproductive performance of ewes treated with synthetic progestogens administered by subcutaneous ear implant or by intravaginal sponge pessary.

Experiments were conducted to compare the efficacy of synthetic progestogens administered by subcutaneous ear implant or intravaginal sponge to induce a synchronized estrus in adult ewes and ewe lambs and to evaluate reproductive performance (fertility and litter size) to breeding at the synchronized estrus. Experimental animals were representative of three strains maintained in total confinement and exposed to a synthetic light regimen which alternated at intervals of 4 mo from 18 h day length to 10 h day length/24 h. Treatments were applied at different times of the year at the end of a low light cycle. Implants contained Norgestomet (3 mg) impregnated in a polymethacrylate polymer (Implant H) or impregnated in a silastic polymer containing 1.05 (Implant S1), 1.78 (Implant S2) or 2.60 mg (Implant S3) Norgestomet, respectively. Intravaginal sponges contained 40 mg Fluorogestone Acetate. Implants or sponges were left in situ for 12 d and 500 IU pregnant mares' serum gonadotropin was injected im at the time of removal. Following treatment with Implant H, 96% of ewes were judged to be in estrus at 48 h after implant removal. Fertility of adult ewes and ewe lambs (6 to 7 mo of age at time of breeding) at the synchronized estrus were similar after implant H or sponge treatment, but litter size was higher (P less than .05) for adult ewes treated with sponges. The percentages of adult ewes marked by rams within 60 h after removal of silastic implants or intravaginal sponges were similar. There was a tendency for ewe lambs to be marked later than adult ewes and for adult ewes treated with Implant S1 and Implant S2 to be marked earlier than ewes treated with Implant S3 or sponges. Higher percentages (P less than .05) of adult ewes and ewe lambs lambed to breeding at the synchronized estrus after treatment with Implant S2 or Implant S3, respectively, than after treatment with Implants S2 or sponges.

Animals↗

The effect of modified eros centre, outdoor raising or conventional group housing on breeding gilts and its effects on reproductive performance over four parities.

The present study was conducted in a large Croatian "built up unit". The objective of the study was to determine if an indoor modified eros centre (MEC) compared to indoor or outdoor group housing of gilts, influenced the onset of puberty of gilts and the reproductive performance of the evaluated females (n = 783) over four parities. The gilts were from the same nucleus herd. Gilts of same age (140-150 days of age), body condition (body condition score of 3-4) and similar genetics (four-way cross females), during the same season (January to April 1999), were randomly divided at arrival into three groups and treated as follows:MEC gilts (n = 279): These were placed into indoor MEC pens in groups of 8-10. The gilts had continuous fenceline contact to boars (one boar to two groups of gilts, boars were changed daily) and to shortly weaned oestrous sows. Gilts were regrouped and dislocated at 10-day intervals. Outdoor gilts (n = 263): These were kept in groups of 8-10 on a large pasture (80-100 m2 per group). The animals had fenceline contact to mature boar for 5-10 min daily. Control indoor gilts (n = 241): These were housed indoors in large pens in groups of 8-10. The animals had fenceline contact to mature boars for 5-10 min daily. Each outdoor group had an insulated hut with straw bedding. All gilts were fed ad libitum with the same commercial diet. Housing gilts in MEC resulted in earlier (P < 0.001) onset of estrus (MEC: 174.8 +/- 2.4 days, indoor group housing: 207.6 +/- 4.1 days, outdoor group housing: 187.4 +/- 2.1 days) and lower (P < 0.001) farrowing rate to first service (MEC: 70.97%, indoor group housing: 89.73%, outdoor group housing: 89.62%). Farrowing rate of regularly returning MEC gilts to second service was 95.00%. First total-born litter size, first liveborn litter size, first wean-to-estrus interval (WEI), percent of sows bred after first weaning, second total-born litter size, second liveborn litter size, average third and fourth total-born and liveborn litter size, number of sows having four litters, number of litters per sow, total number of pigs per sow, total number of liveborn pigs per sow showed no significant differences between the groups. More (P < 0.05) sows were culled in outdoor group. Compared to MEC and outdoor housing, indoor housed sows suffered higher (P < 0.05) percentage of anoestrus.

Animals↗

Influence of a deficient intake of high and low degradable protein on body composition, metabolic adaptation, production and reproductive performance in early lactation dairy cows.

High-yielding dairy cows (n = 34) were divided into high (HD) and low (LD) protein degradability groups after delivery, and used for a feeding trial which lasted up to day 80 +/- 10 of lactation. The cows were regularly weighed, their body condition was scored (BCS), and their reproductive status assessed. Blood samples were taken simultaneously, and ruminal fluid was collected on the last day of the trial. On postpartum day 45 +/- 6 and 11 days thereafter two prostaglandin F2 alpha (PGF2 alpha) injections were administered. The ammonia and urea concentrations of the ruminal fluid were higher in cows of group HD. The C2:C3 ratio was 2.7:1 vs. 2.3:1 in HD and LD cows, respectively. The amino acid and lipid composition of blood reflected the dietary treatments. The BCS and blood urea concentration were slightly higher in HD animals. The average daily milk production of LD cows was 1.5 kg higher than that of HD cows. The pregnancy rates of the two groups at day 200 after calving did not differ, but LD cows showed their first visible oestrus and reconceived significantly (p < 0.05) later. It can be concluded that--at a marginal energy supply-a moderate (13%) deficiency of rumen-degradable protein during the first 10 weeks after calving can be more detrimental to reproductive performance than a severe (27%) deficiency of undegradable protein.

Adaptation, Physiological↗

Growth and reproductive performance of rabbits on a moderately low crude protein diet with or without methionine or urea supplementation.

The reproductive and growth performances of New Zealand White rabbits on four dietary treatments were compared. The treatments were a 21.5% crude protein (CP) diet control, a 16% CP diet (LP), LP + .3% DL-methionine (LP + met) and LP + 2.1% urea (LP + urea). The CP in the LP diet was derived entirely from alfalfa meal and wheat mill run, with no protein supplement used. Data were collected over five parities. Preweaning and postweaning growth rates and reproductive performance as assessed by litter size, conception rate and litter interval, were comparable for the four treatments. Average daily postweaning gain was about 40 g per d. Litter size at weaning was seven kits per litter. This study indicates that a simple diet of forage and a grain-milling by-product, with no cereal grain or protein supplement, can support normal growth and reproduction of commercial meat rabbits.

Animals↗

Influence of undegraded intake protein supplementation on milk production, weight gain, and reproductive performance in postpartum Brahman cows.

Eighty first-calf Brahman heifers and 51 mature Brahman cows were allotted to one of three diets based on parity, sex of calf, and breed of calf sire (Angus, Brahman, or Tuli) to evaluate rumen undegraded intake protein's (UIP) influence on production characteristics and reproductive performance. Supplements contained either 38.1% (low), 56.3% (medium), or 75.6% (high) UIP. Supplements were given from d 7 to 119 after calving to dams grazing rye-ryegrass overseeded Coastal bermudagrass pastures and with access to Coastal bermudagrass hay. Dam and calf BW and dam body condition score were recorded on d 7, 35, 63, 91, and 119 after calving. Four-hour milk production was recorded on the above days for low (n = 18), medium (n = 19), and high (n = 18) UIP animals and on d 7 and 35 for the entire group. Blood for progesterone RIA was drawn weekly and on d 6, 8, 10, and 12 after an observed estrus. Medium UIP heifers produced more (P < .02) milk (1.18 +/- .07 kg/4 h) than high UIP heifers (.94 +/- .07 kg/4 h), but milk production in mature cows was not influenced by diet. Low UIP dams had lower (P < .04) first-service conception rates (29.2%) than medium (57.6%) and tended (P < .10) to have lower rates than high UIP dams (54.6%). Overall pregnancy rates tended (P < .10) to be higher in medium (61.5%) and high (56.4%) UIP groups than in the low (43.2%) UIP group. Supplementing UIP at the medium rate improved first-service conception rates and tended to improve pregnancy rates.

Animal Feed↗

Effect of different bedding materials on the reproductive performance of mice.

Vermiculite, pine shavings and unbleached eucalyptus pulp contact-bedding were compared using the number of litters and individuals born and weaned, mortality rates at different stages of the lactation period, and the weight increase of pups as evaluation indices for bedding quality. These bedding materials exerted different effects on the reproductive performance of the same mouse strain. The same is true for the effect of a specific bedding material on different mouse strains. These effects are most pronounced during the first 4 days of life. As a whole, the results demonstrated that eucalyptus pulp was the better bedding type, followed by pine shavings and vermiculite. The latter material had a detrimental effect on the mating success of AKR mice.

Analysis of Variance↗

Reproductive performance in a breeding colony of Brazilian squirrel monkeys (Saimiri sciureus).

In a captive colony of Brazilian squirrel monkeys (Saimiri sciureus) a discrete birth season has been retained for 5 years although its duration increased from 3 months in 1972 to 6 months in 1976. The ages of breeder females in this colony ranged from 3 to 14 years, and within this range reproductive performance was not affected by age, although it was significantly better in feral than in colony-born females. The latter had a lower pregnancy rate and a higher incidence of neonatal and fetal deaths than did the feral monkeys. It is our belief that the reproductive and maternal capabilities of the colony-born females were adversely affected by the practice of removing neonates from their mothers at weaning and raising them with age-mates.

Animals↗

Gonadotropin-releasing hormone improves reproductive performance of dairy cows with slow involution of the reproductive tract.

Eighty multiparous Holstein cows were assigned randomly at calving to receive either 100 microg of GnRH or saline 13 or 14 d postpartum (PP). From 4 to 28 d PP the cows' reproductive organs were palpated weekly per rectum, and cows were subclassified within each group as undergoing slow (delayed) cervical and uterine involution (abnormal) or as normal cows. Last milk obtained after removing the milking machine was assayed for progesterone 3 times a week for 120 d PP. Fourteen of the 80 cows were removed from the experiment because of culling or various veterinary treatments of pathologic conditions that could confound analysis of the GnRH treatment effects. As expected, the treatment of normal cows with GnRH had no significant effects on the first estrus or the first estrous cycle PP, on services per conception, days open, or any other reproductive trait measured. However, in the abnormal group of cows receiving saline, first rebreeding after calving was delayed (81 vs. 67 d), fewer were pregnant by 105 d PP (23 vs. 64%), and number of days open was greater (121 vs. 87 d) compared with those receiving GnRH; all were significant (P<.05). Treated abnormal cows were equivalent to the control normal cows. Thus, GnRH given 13 to 14 d PP to cows characterized as undergoing slow involution of the reproductive system, but with no other clinical problems, seems to assist in promoting rapid normal reproductive function. Subsequent losses due to culling were greatly reduced.

Animals↗

Effect of levamisole on immune function and reproductive performance in first-litter gilts.

First-litter commercial cross-bred gilts were treated with levamisole (1.5, 2.5, or 3.5 mg/kg of body weight) weekly during the last 4 weeks of gestation, because similar treatment of dairy heifers had improved postpartum maternal health and neonatal survival. In the gilts, differences in reproductive performance were not found on the basis of pig survival at birth, pig survival at weaning, birth weight, or weaning weight. Also, differences between treated and control gilts were not found in response of circulating lymphocytes to mitogen stimulation (phytohemagglutinin A, concanavalin A, and pokeweed mitogen). In all gilts, the lymphocyte response to mitogen stimulation was decreased during the first week after farrowing.

Animals↗

Reproductive performance of farmed red deer (Cervus elaphus) in New Zealand. IV. Biological markers as risk factors for yearling and adult hind conception.

A 2-year observational study of 15 red deer (Cervus elephus) farms was carried out in New Zealand from March 1992. In each year of study, approximately 1650 hinds were individually monitored for reproductive success. During farm visits in March 1992 and 1993, five yearling and five adult hinds per farm were randomly selected and blood sampled to define their haematological, biochemical and blood mineral profile. Faecal samples were taken for parasite egg and larvae count. Biological markers potentially affecting the probability of conception before May 1 or of conception that year were investigated separately using multivariable logistic regression analysis. Adult hinds with low serum phosphorus concentrations were more likely to conceive before May 1. Lower conception rates were observed in yearling hinds when blood glutathione peroxidase, serum vitamin B12, and serum albumin concentrations were low, and when faecal lungworm larval counts were high. While these associations have yet to be proven as causal, data suggests that monitoring and maintaining adequate blood elements, and controlling internal parasites in yearling hinds, may assist farmers to achieve optimum reproductive performance in farmed red deer herds.

Animals↗

Dietary essential fatty acid supplementation, urinary calcium excretion and reproductive performance in the diabetic pregnant rat.

Hypercalciuria may be a contributory factor to the disturbed calcium homoeostasis seen in diabetic pregnant rats and their offspring. In diabetes, essential fatty acid metabolism is impaired. We have therefore investigated whether feeding a diet supplemented with essential fatty acids will ameliorate the hypercalciuria of diabetic pregnancy and improve reproductive performance. Female rats were fed a standard rat diet, a fat-free diet plus evening primrose oil or a fat-free diet plus sunflower oil. They were injected with streptozotocin or vehicle and mated. Urine samples were analysed for calcium before injection and during gestation. Term-pregnant diabetic rats fed evening primrose oil showed a 73% reduction in urinary calcium output compared with similar rats fed standard diet (P < 0.001). The corresponding reduction was 44% in diabetic rats fed sunflower oil (P < 0.001). A depletion of essential fatty acids in diabetes may therefore be associated with hypercalciuria; dietary supplementation, particularly with evening primrose oil, appears to correct the problem. Diabetic pregnant rats fed evening primrose oil showed a significantly greater live fetal mass (85 +/- 2 vs 33 +/- 12 g; P < 0.05) compared with similar rats fed standard diet. Such findings may imply a normalization of placental transport by essential fatty acids. Rats fed evening primrose, but not sunflower oil, also showed a reduced incidence of diabetes after streptozotocin injection compared with rats fed standard diet (63 vs 86%). Rats fed on evening primrose oil that did become diabetic were less hyperglycaemic than those on the standard diet (29 +/- 2 vs 37 +/- 2 mmol/l), suggesting that the oil may have anti-diabetic properties.

Animals↗

Assessment of the influence of dietary vitamin E on sows and offspring in three parities: reproductive performance, tissue tocopherol, and effects on progeny.

Sixty crossbred (Yorkshire-Hampshire X Duroc) gilts were fed one of four corn-soybean meal diets fortified with .3 ppm Se and 0, 16, 33, or 66 IU of DL-alpha-tocopheryl acetate/kg. The study was conducted over a three-parity period to evaluate sow reproductive performance and the vitamin E tissue status of both sows and progeny at various time periods postcoitum and(or) postpartum. The basal diet averaged 8.4 mg of alpha-tocopherol/kg and .38 ppm of Se. Although litter size at birth was lowest (P less than .15) when sows were fed the basal diet, a higher incidence of agalactia when sows were fed the lower dietary vitamin E levels resulted in an increased (P less than .05) litter size at 7 d postpartum as dietary vitamin E increased. Sow serum alpha-tocopherol increased (P less than .01) at each measurement period as dietary vitamin E level increased. Colostrum and milk alpha-tocopherol concentrations increased (P less than .01) as dietary vitamin E level increased, and colostrum values were three to five times higher than at later milks. Colostrum alpha-tocopherol declined by parity from sows fed less than or equal to 16 IU/kg but was similar at each parity for sows fed greater than or equal to 33 IU/kg, resulting in a dietary vitamin E x parity interaction (P less than .01). The Se content of sow milk declined with parity but was not affected by dietary vitamin E level. Sow liver tocopherol at weaning (28 d postpartum) increased (P less than .01) as dietary vitamin E increased and increased with parity (P less than .05). Pig serum and liver alpha-tocopherol concentrations were elevated at birth and 7 and 28 d of age as sow dietary level of vitamin E increased. Upon weaning, pigs were fed a torula yeast-dextrose diet that contained 3.0 mg of alpha-tocopherol/kg and .32 ppm Se for a 28-d postweaning period. Liver and serum alpha-tocopherol concentrations declined during the postweaning period. Evidence of the vitamin E deficiency occurred at 28 d postweaning in the progeny from sows fed the basal diet or 16 IU of vitamin E; the incidence was more prevalent in the pigs from Parities II and III. These results suggest that a supplemental level of 16 IU of vitamin E/kg of diet was inadequate for the reproducing sow; higher levels are justified, particularly when females are retained in the herd for several parities.

Animal Feed↗

Effects of evaporative cooling on reproductive performance and milk production of dairy cows in hot wet conditions.

Fourteen animals of second and third lactation of Thai Friesian crossbred cows (87.5% Friesian x 12.5% Bos indicus) located at Sakol Nakhon Research and Breeding Centre, Department of Livestock Development, Ministry of Agriculture and Cooperatives, were divided randomly into two groups of seven each to evaluate the effects of evaporative cooling on reproductive and physiological traits under hot, humid conditions. Results indicated that installation of evaporating cooling in the open shed gave a further improvement in ameliorating heat stress in dairy cows in hot-wet environments by utilising the low humidity conditions that naturally occur during the day. The cows housed in an evaporatively cooled environment had both a rectal temperature and respiration rate (39.09 degrees C, 61.39 breaths/min, respectively) significantly lower than that of the non-cooled cows (41.21 degrees C; 86.87 breaths/min). The former group also had higher milk yield and more efficient reproductive performance (pregnancy rate and reduced days open) than the latter group. It is suggested that the non-evaporatively cooled cows did not gain benefit from the naturally lower heat stress during night time.

Animals↗