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1.
The objectives of this study were to describe the serum selenium (Se) concentrations of beef cows from herds with varying levels of reproductive success, to examine factors associated with the Se concentrations at the end of the grazing season, and to determine if there were any associations between serum Se and reproductive success or calf viability. In the fall of 2001, 781 serum samples from 66 herds were analyzed as part of a nested case-control study to investigate risk factors for fertility; 10.6% were deficient in Se (< 0.025 ppm) and 86.8% were less than adequate (< 0.08 ppm). Low serum Se was most common in thin cows where feed Se was < 0.2 ppm, and from areas with more precipitation or with black or gray soils. Serum Se at pregnancy testing was not associated with an increased risk of reproductive failure. Lower herd serum Se was associated with increased risk of identifying degenerative myopathy in the subsequent calf crop (P = 0.006).  相似文献   

2.
Herens cows have been treated at the Clinic for Ruminants, University of Berne, more frequently for fertility problems than other breeds. The aim of the study was to overview the reproductive performance of the Herens breed by analyzing data sets of the Herens Breeding Book and of the Animal Traffic Database of Switzerland. In addition, a questionnaire was sent to the breeders concerning aspects of management and care to identify a possible influence on the reproductive performance of the animals. Based on 4988 lactations starting in 2003, an average interval of calving to first insemination of 86 days a calving to conception interval of 146 days and an inter calving period of 431 days could be calculated. Conception rate resulted in 39.1%, the fertility index was 1.87 and 6.5% of all cows were culled because of fertility problems. Half of the breeders owned 4 or less cows. The most important reason for keeping Herens cows was cow fighting. Traditional alpine pasturing and cow fight rules resulted in a seasonal calving with 80% of the births taking place between October and December. The calving month and seasonal calving were the most important reasons for a prolonged calving to conception interval.  相似文献   

3.
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4.
An observational study was conducted to quantify the effects of management practices on reproductive performance and disorders of beef cows. The study population consisted of 44 randomly selected Colorado cow-calf herds monitored for disease and reproductive events as part of the National Animal Health Monitoring System. The managers of the herds were surveyed with a standardized questionnaire to determine specific management characteristics of their operations. Data were analyzed using the random-effects multiple logistic regression model. Outcomes of interest were calving rate, herd incidence rates of dystocia and combined reproductive disorders, and calf mortality rate. A higher calving rate was associated (P less than .01) with a decreased percentage of replacement females in the herd, a shorter breeding season, a smaller herd size, and a lower percentage of bulls being used as yearlings. Incidence rates of both dystocia and combined reproductive disorders were found to be lower (P less than .01) in herds that were fed cottonseed cake as a winter supplement, but higher (P less than .01) in herds that were fed grass hay as a winter supplement. Herds located in the mountains of Colorado had lower (P less than .01) incidence rates of dystocia and reproductive disorders than herds located in the eastern plains. Calf mortality rate was found to be higher (P less than .05) with calving seasons that began earlier in the year. Higher calf mortality rates were associated (P less than .05) with an increased incidence of dystocia, the commingling of cattle on summer range, and smaller herd size.  相似文献   

5.
One thousand and eighty-five newly received, stressed calves were used in studies to determine the effectiveness of certain mass medication procedures for reducing morbidity from shipping fever-bovine respiratory disease complex. In two experiments, im injections of oxytetracycline at 11 mg/kg body wt for 3 successive days reduced treatment days/calf purchased 21 (P less then .05) and 31% (P less than .05). Oral administration of 150 mg of sulfadimethoxine/kg body wt reduced treatment days/calf purchased 20 (P less than .05) and 54% (P less than .05) in the same two experiments. When sulfadimethoxine followed oxytetracycline on the third injection day an 81% reduction in treatment days/calf purchased was obtained, indicating an additive effect of the two drugs. The use of long acting oxytetracycline and sustained release sulfadimethoxine at the time of processing resulted in a 90% reduction in treatment days/calf purchased (P less than .01) and required only one handling of the calves for mass medication purposes.  相似文献   

6.
The reproductive performance of 76 Sanga cows was studied from February 1995 to July 1996 in smallholder peri-urban dairy systems in the coastal savanna zone of the Accra plains of Ghana. The interval from calving to resumption of cyclic ovarian activity was 101±7 days; that from calving to conception was 152±4 days; gestation length was 292±16 days; and the calving interval was 444±16 days. The effects of location, season of calving, parity, body condition score and sex of calf were studied. Calving to cycling interval was significantly shorter in the dry season than in the wet season, and decreased significantly with increasing body condition score. Calving to conception interval was affected only by location. Gestation length was not affected by any of the variables studied. Calving interval was affected by location, season of calving, parity and body condition score. It is concluded that long post-partum anoestrus leads to prolonged calving intervals and poor reproductive performance. Feed supplementation to improve the nutritional status and body condition score of cows and early weaning of calves could be introduced to enhance reproductive performance.  相似文献   

7.
The efficacy of using a bolus containing morantel in a sustained-release preparation for controlling naturally acquired gastrointestinal parasitic infections in weaned calves and yearling cattle was investigated during the 1982 grazing season at selected sites in the United States and Canada. According to a common trial design under various climatic and management conditions, 10 field trials were conducted with the bolus. At the time of spring turnout, a bolus was administered to each calf or yearling in the treated group. Then, treated and control cattle grazed separate but equal areas of divided pasture(s). The epidemiologic pattern of parasitic gastroenteritis in control animals and the effect of treatment on this pattern was determined in each trial. Safety and practicality of use of the bolus also were established. When compared with untreated cattle (control), those given the bolus deposited significantly (P less than 0.05) fewer worm eggs (89% reduction) during the first 90 days of the grazing season, as well as significantly fewer (P less than 0.05) worm eggs (84% reduction) during the entire grazing season. Consequently, during the second half of the grazing season, larval populations on treated pastures remained significantly (P less than 0.05) lower (66% reduction), compared with numbers of larvae found on control pastures. For pastures grazed by treated and control cattle at trial initiation, mean worm counts recovered from tracer calves were equal, indicating comparable pasture contamination at the beginning of the grazing season.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

8.
OBJECTIVE: To determine the effect of induction of parturition on health, milk production and reproductive performance of dairy cows. DESIGN: A prospective cohort study in 62 dairy herds. PROCEDURE: Health, milk production and fertility indices were documented for 1449 dairy cows treated with dexamethasone trimethylacetate, with or without prostaglandin to induce calving. Equivalent data was collected for 603 untreated herd mates that calved at approximately the same time. RESULTS: The median interval from initial treatment to calving was 11 days. Induction was associated with a substantially lower calf survival and commercial value of surviving calves. Calf viability and value was lower when induced cows were at an earlier stage of pregnancy. Retained foetal membranes, photosensitisation and other problems were significantly more frequent in the induced group compared to the untreated group. Milk production of induced cows was approximately 4% lower than untreated ones, but the majority of reproductive indices were not significantly different between the two groups. CONCLUSIONS: The practice of induction of parturition in seasonal calving dairy herds is a reliable way of shortening the gestation period of cows. Costs associated with morbidity and mortality of induced cows and losses in lactation and calf production are offset by benefits of improved reproductive performance and more efficient management of the herd. The welfare aspects of induction on calf survival must be considered.  相似文献   

9.
The aim of this study was to evaluate the effect of body weight (BW) change during the early postpartum period and BW on day 50 post partum on the subsequent expression of estrus and fertility at first insemination before day 90 post partum. The data were derived from 1036 postpartum cows reaching 90 days in milk. The following data were recorded for each animal: lactation number, daily milk production at day 50 post partum, calving date, days in milk at estrus and at AI, insemination date, insemination number, inseminating bull, AI technician and body weight at calving, at day 50 post partum and at AI. Of the 1036 cows registered, 817 (78.9%) showed first estrus before day 90 post partum and were inseminated. Using logistic regression procedures and based on the odds ratio a one unit (kg) increase in the daily milk production at day 50 post partum and a one unit (kg) decrease in the BW between calving and day 50 post partum were related to a 1.03-fold increase and a 0.97-fold decrease in the estrus expression rate before day 90 post partum, respectively. Of the 817 cows inseminated before day 90 post partum, 437 became pregnant (53.5%). A one unit increase in the BW at day 50 post partum produced a 1.003-fold increase in the early fertility rate. Pregnancy rate before day 90 was also influenced by the season at calving, bull providing semen and technician. In conclusion, the register of BW during the postpartum period may be a useful tool for evaluating the nutritional status and its relationship with the subsequent reproductive efficiency in dairy cows.  相似文献   

10.
Relative date of first calving of beef heifers was studied in relation to production efficiency and subsequent reproductive performance. Crossbred heifers were managed in a drylot environment for 1 yr with feed intake measured through weaning of the first calf. Mean heifer age at entry into drylot was 572 d. Production traits were evaluated by calving group (CG), where CG1 included records of heifers calving (and calves born) in the first 21 d of the calving season for a particular year, CG2 included those calving from 22 through 42 d and CG3 included those calving after 42 d. Calving groups did not differ significantly for preweaning calf ADG, but weaning age differences resulted in heavier weaning weights for CG1 compared with CG2 and CG3. An earlier relative calving date was associated with increased cumulative feed energy intake of heifers and their calves during the 1-yr test period. In terms of production efficiency, the weaning weight advantage of earlier calving was offset only partly by the increased feed energy intake of the dam-calf unit, resulting in 6.3 Mcal (12.4%) less ME per kg calf weaning weight for CG1 vs CG3 for the 1-yr period. Within a limited calving season, earlier calving dams tended to be biologically and economically more efficient because a greater proportion of their annual production cycle was in a productive (lactating) mode, diluting maintenance costs as a fraction of all costs. Heifers in CG1 also tended to calve earlier than CG3 heifers for the second calf. Calving interval was a biased measure under the management conditions of a limited breeding season and culling of open cows.  相似文献   

11.
Measures of herd health and productivity in Ontario cow-calf herds   总被引：2，自引：1，他引：1       下载免费PDF全文
A cohort of cows and heifers in 180 separate breeding herds from 170 randomly sampled farms was followed from the 1986 breeding season through to the weaning of their calves in 1987. Data were collected from farm records, survey information collected during farm visits, and provincial government weaning-weight records.

“Kilograms of calf weaned per female-exposed-to-breeding” was calculated as a summary measure of herd productivity. The lowest 25% of cow-herds produced less than 160 kg of calf weaned per cow-exposed-to-breeding, while the highest 25% exceeded 205 kg.

Overall calf crop was 78.1% for cows and 78.5% for heifers. The 25th, 50th, 75th, and 90th percentile estimates for rates, which were components of calf crop (e.g. calving rate), were estimated. The component rates that most influenced calf crop were culling rate for cows and stillbirth rate for heifers.

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12.
The objective of this study was to analyse the effect of dystocia on calf viability, milk production, fertility and culling under field (farm) conditions in a retrospective case-control study. A total of 253 calvings that were attended by a veterinarian were classified into three categories: mild dystocia (MD), severe dystocia (SD) and caesarean section (CS). For every case of dystocia, a control was chosen from the same farm and matched for calving month, breed and parity. Cases and controls were compared concerning calf viability, milk production, fertility and culling. The proportion of stillbirths was significantly higher in cows with dystocia compared with their controls. However, the difference was lower in CS cows than in the other two groups. MD had no significant effects on milk production, fertility and culling. There were no obvious effects of SD on monthly test day milk production, while CS cows produced significantly less milk than their controls. Compared with controls, less SD (50.0% versus 61.6%) and CS cows (48.6% versus 70.3%) conceived until 200 days in milk and more CS cows (31.1% versus 16.2%) were culled in the same time interval. These data demonstrate the scope of economic and animal welfare opportunities associated with the reduction of dystocia by management and breeding.  相似文献   

13.
Forty sows comprising equal numbers of Landrace (LR) and Large White (LW) breeds were studied for 20 months to determine the effects of dry and rainy seasons on their fertility traits in Nigeria. Ambient temperature (14.0-35.5 degrees C) was lowest at night and highest in the day and peaked during the dry season. A relative humidity range of 60-82% peaked during the late rainy season. LR produced 218 and 278 piglets from 23 and 28 litters, while LW produced 193 and 316 piglets from 20 and 30 litters during dry and rainy seasons respectively. Fertility traits did not differ significantly between the breeds due to season (P greater than 0.05). Mean post-weaning oestrus at 10.9 and 9.0 days and preweaning mortality rates of 14.2% and 16.9% during dry and rainy seasons for LR differed significantly (P less than 0.5) from those of LW which were 12.2 and 8.2 days and 14.5% and 18.9% respectively. The significance of seasonal effects on sow fertility and necessary management techniques are discussed.  相似文献   

14.
Two experiments evaluated prebreeding target BW or progestin exposure for heifers developed lighter than traditional recommendations. Experiment 1 evaluated the effects of the system on heifer performance through subsequent calving and rebreeding over 3 yr. Heifers (229 kg) were assigned randomly to be developed to 55% of mature BW (299 kg) before a 45-d breeding season (intensive, INT; n = 119) or 50% of mature BW (272 kg) before a 60-d breeding season (relaxed, RLX; n = 142). Prebreeding and pregnancy diagnosis BW were greater (P 0.15) between systems. Cost per pregnant 2-yr-old cow was less for the RLX than the INT heifer development system. Of heifers that failed to become pregnant, a greater proportion (P = 0.07) of heifers in the RLX than in the INT system were prepubertal when the breeding season began. Therefore, a second 2-yr experiment evaluated melengestrol acetate (MGA, 0.5 mg/d) as a means of hastening puberty in heifers developed to 50% of mature BW. Heifers were assigned randomly to the control (n = 103) or MGA (n = 81) treatment for 14 d and were placed with bulls 13 d later for 45 d. Prebreeding and pregnancy diagnosis BW were similar (280 and 380 kg, respectively; P > 0.10) for heifers in the control and MGA treatments. The proportion of heifers pubertal before breeding (74%), pregnancy rate (90%), calving date, calf weaning weight, and second breeding season pregnancy rate (92%) were similar (P > 0.10) between treatments. Developing heifers to 50 or 55% of mature BW resulted in similar overall pregnancy rates, and supplementing the diets of heifers developed to 50% of mature BW with MGA before breeding did not improve reproductive performance.  相似文献   

15.
The objective of the present research was to evaluate the effect of a calf's genetic group on the productive and reproductive efficiency of its Nellore dam. Fixed‐time artificial insemination was applied to 800 cows using semen extracted from Nellore, Simmental and Angus Red bulls. Four hundred eleven cows calved, producing 119 Nellore, 103 ½Simmental–½Nellore and 189 ½Nellore–½Angus Red calves. The second mating period, which paired Nellore cows with Simmental bulls, was initiated 10 days after parturitions began and lasted for 5 months. Based on the two successive parturitions, the cumulative parturition rate for calving periods of 3, 4 and 5 months was calculated. Although no significant difference was observed for birth weight among the genetic groups, cross‐bred calves weighed, on average, 10% more than did pure‐bred calves at the age of 205 days. Nellore dams experienced a gestation period that was 7 days longer than did the cross‐bred dams, and the former showed a higher parturition rate at 90 and 120 days of the calving season, but not at 150 days (calving rates of 80.6, 76.4 and 76.2% for mothers of Nellore, ½Nellore–½Angus Red and ½Nellore–½Simmental, respectively, p > 0.05). At 90 and 120 days, Nellore dams produced more kg of calf per mated dam. In conclusion, in a short breeding season, Nellore dams nursing pure‐bred Nellore calves were found to have a higher biological efficiency compared with Nellore dams nursing cross‐bred calves.  相似文献   

16.
The objective of this study was to document mortality reasons and risk factors for mortality in dairy calves in the northeast of Iran. This was a prospective cohort study of calves born on ten commercial dairy herds from 21 March 2009 to 20 March 2010. A total of 4097 live calves were followed for 90 days after birth. For each calf details of sex, parity of the dam, type of parturition and season of birth were recorded. The interval (in days) from the date of birth to the date of death and the reason for death was recorded for those calves that died before 90 days of age. A Cox proportional hazards model, including a frailty term to account for unmeasured herd-level effects was developed to quantify the effect of factors associated with time to death. Two hundred and sixty-six (6.5%, 95% CI: 5.8-7.3%) of the 4097 live-born calves died or were euthanised before 90 days of age. The most important reasons for death were digestive tract disorders (58% of all deaths, 95% CI: 52-64%) followed by respiratory diseases (13% of all deaths, 95% CI: 9-17%). Calves exposed to dystocia at birth had 2.09 (95% CI: 1.49-2.92) times the daily hazard of death compared with calves born from a normal calving. The daily hazard of death for calves born in the summer was 1.93 (95% CI: 1.41-2.64) times greater than the hazard for those calves born in the autumn. Inclusion of the herd-level frailty term had a significant effect on hazard estimates indicating that the study herds were heterogeneous in the distribution of unmeasured herd-level factors influencing calf survival. Our results show that diarrhoea is the most important cause of calf mortality in dairy herds in this area of Iran and that environmental and management factors affect calf mortality rate.  相似文献   

17.
为了研究母牛高效繁育技术对平凉红牛母牛繁殖效率和养殖效益的影响,从母牛产后第8天开始,试验组母子分离、定时哺乳、早期断奶,对照组随母哺乳、自然断奶。结果表明,试验组母牛主要在60 d内第一次发情,发情率76.7%,对照组母牛主要在90 d后第一次发情,发情率60%;试验组母牛90d内受胎率86.7%、第一次授精情期受胎率89.7%,分别比对照组高53.3%、6.4%。存栏能繁母牛120头的适度规模场,通过母牛一年一胎繁育技术措施每年可新增纯收益12.8万元,效益可观。  相似文献   

18.
Sixty Holstein cows were paired by parity and sire, and one of each pair was allocated at random to treatment or control; 17 cows were injected with 7.5 mg/100 kg dexamethasone trioxa undecanoate 14 days before the predicted date of calving, 13 cows received the same dose five days before term and 30 cows were left untreated. The treatment significantly advanced parturition and 29 of the 30 induced cows calved within 72 hours of the injection. Induction at day 14 before term was safe for calf and dam, the calves were 3.2 kg lighter than control calves and there was a high incidence of retained placenta. Treatment for this condition resulted in increased veterinary costs of 14.50 pounds per cow exclusive of dexamethasone treatment. Treatment at this stage was also associated with low pregnancy rates in the next breeding season. Calves born after induction at five days before term were not significantly lighter than calves from control cows, the problem of retained placenta was less marked and there were no subsequent effects on fertility. There were no significant effects of induction on milk yield or milk quality up to 200 days of lactation.  相似文献   

19.
The sexual season, i.e. the sexual cycle activity, of Finn × German Mutton Merino (Finn × GMM) ewes was found to extend from August to March. In a group of purebred German Mutton Merino (GMM) ewes the sexual season extended from June to January.After July–August and October–November lambings, 90–95% of the Finn × GMM crosses renewed postpartum sexual activity within 90 and 75 days, respectively. Only 40% of the November lambing purebred GMM ewes started new cycles within 105 days postpartum.The responsiveness of the Finn × GMM ewes to hormonal treatment was high (90–100%) during different months of the year. The fertility at the synchronized or induced oestrus was 60–75% throughout the year, with a mean litter size of 2.0 lambs per lambing.  相似文献   

20.
Reproductive data were collected on 4,595 cow exposures and subsequent calvings over four generations in a rotational crossbreeding study involving Angus, Brahman, Charolais and Hereford breeds. Direct and maternal additive (Ig and Mg) and nonadditive (Ih and Mh) genetic effects were estimated for calving rate, calf survival, weaning rate, calving assistance and calf birth date. Genetic effects were estimated by regressing individual animal response on the proportion of genes from breed of origin and gene combinations expected for the four breeds in offspring and in dams. Breed direct and maternal additive and nonadditive genetic effects were expressed as a deviation from the least squares mean. Brahman Ig effects decreased calving and weaning rate (-9.5 +/- 4.0 and -11.8 +/- 4.4%) but Mh effects for weaning rate that included Brahman were positive, ranging from 16.5 +/- 6.7% for Angus-Brahman to 27.8 +/- 6.9% for Brahman-Hereford. The Brahman Ig effect delayed calf birth date (9.8 +/- 2.1 d; P less than .01), whereas Angus and Hereford Ig effects influenced earlier calf birth dates (-4.3 +/- 1.9 and -4.1 +/- 1.9 d; P less than .05). Brahman combination Mh effects also influenced earlier calf birth dates (P less than .01). The Charolais Ig effect for calving assistance was positive (4.3 +/- 1.9%; P less than .05), whereas Angus-Brahman and Brahman-Charolais Mh effects for calving assistance were negative (-6.5 +/- 3.2 and -7.0 +/- 3.2%; P less than .05) and more desirable. Predicted reproductive traits for rotational mating systems were intermediate between predicted reproductive traits for two- and three-breed terminal crosses. Predicted calving and weaning rates were maximized when Brahaman first-cross and Charolais-Hereford cows were used in three-breed cross mating systems.  相似文献   

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