Factors influencing calving difficulty in beef heifers

Records of 547, 2-yr-old heifers of three breed groups were used to evaluate the relative influence of dam's body and pelvic measurements, calf birth weight, sire birth weight and some relative measures (ratios) of calf birth weight and dam weight at calving on calving difficulty. The data were analyzed by regression and least squares procedures. The full model explained 32.5% of the variation in calving difficulty score. The linear effect of calf birth weight was the most important variable, accounting for 17.8% reduction in the coefficient of determination, and together with dam weight at calving and the quadratic effect of calf birth weight it accounted for 92% for all the variation explained by the full model. Dam weight at calving was negatively related to calving difficulty. Breed, year and sex of calf did not influence calving difficulty score, except when the calf birth weight or dam weight or both were excluded from the model. When calf birth weight was expressed as a ratio of the dam's weight at calving, hip height and pelvic measurements, the total model explained 34.8% of the variation in calving difficulty score. The ratio of calf birth weight to dam weight was the most important variable (R2 = 26.8%). Ratios of calf to dam weight at calving and calf weight to the vertical pelvic diameter (R2 = 29.3%) were the only significant factors when the effects of calf birth weight and dam weight were removed from the model. Pelvic measurements, on their own, did not influence calving difficulty score in this study (P greater than .1), but small pelvic dimensions tended to be associated with higher calving difficulty scores.     

Factors affecting dystocia and offspring vigour in different sheep genotypes

Birth difficulty and poor lamb vigour are significant causes of perinatal lamb mortality. In this study we investigated whether sheep breeds differing in appearance, muscularity and selection history also had differences in dystocia and lamb vigour, and considered some of the factors that may contribute to the variation in these traits. Data were collected at birth from a total of 3252 lambs of two terminal sire breeds selected for lean growth (Suffolk [S], n = 500 and Texel [T], n = 1207), from a Hill breed (Scottish Blackface [B], n = 610), which has been mainly selected for hardiness, and a crossbred (Mule × T [M], n = 935) representing a maternal line. For each lamb the degree of assistance at delivery, lamb presentation, amount of assistance to achieve successful sucking, sex, litter size and birth weight were recorded. T lambs required the most, and B and M lambs the least assistance at birth, S lambs were intermediate (% lambs assisted: T = 55.7, S = 30.7, B = 22.7, M = 24.9, P < 0.001). T and S lambs were equally likely to be malpresented at birth (29% of births) and more likely to be malpresented than B or M lambs (20%; P < 0.001). In T and S breeds lambs requiring veterinary assistance at delivery were mainly heavy and singleton lambs, whereas in B and M breeds these were exclusively low birth weight lambs in multiple litters. Although heavier lambs needed greater birth assistance, T lambs were lighter than S and M lambs, but heavier than B lambs (birth weight (kg): S = 4.66, M = 4.56, T = 4.32, B = 3.67, P < 0.001). S lambs were more likely to require assistance with sucking than other breeds, and T lambs also required more assistance than B or M lambs (% lambs assisted to suck: S = 56.0, T = 31.6, M = 19.8, B = 18.4, P < 0.001). Heavier lambs were more likely to suck unaided than lighter lambs (P < 0.001). The data suggest that the two terminal sire breeds, selected narrowly for greater productivity (muscle growth and conformation), are more likely to experience birth difficulty and poorer lamb vigour than the breed selected for hardiness, or the cross breed. Whether these effects arise as a consequence of genetic selection (e.g. for specific lamb conformation), or as a result of management practices to achieve selection goals (e.g. increased intervention at lambing) is unknown. Specific actions to improve birth difficulty and lamb vigour, such as including these traits in the selection index, would be beneficial in improving the welfare of ewes and lambs of the terminal sire breeds.     

Factors affecting dystocia and birth weight in Grati cattle in Pujon,East Java

Summary

This paper discusses factors affecting dystocia and birth weight in Grati cattle in three villages in the Pujon district, East Java. Records of birth weight, dystocia score, village, season, parity, sex, artificial versus natural service, and age and weight of dam, were obtained from 268 parturitions. Village and weight of the dam had a significant effect on birth weight but not on dystocia. Parity had a significant effect on dystocia score. More abnormal births occurred with Al using exotic bulls. Calves from an abnormal birth were on average more than three kg heavier. First parity births combined with A1 with exotic bulls had a particularly high incidence of dystocia. It is concluded that farmers in Pujon can reduce the incidence of dystocia in heifers by using local bulls only.     

Factors affecting dystocia and birth weight in Grati cattle in Pujon, East Java

This paper discusses factors affecting dystocia and birth weight in Grati cattle in three villages in the Pujon district, East Java. Records of birth weight, dystocia score, village, season, parity, sex, artificial versus natural service, and age and weight of dam, were obtained from 268 parturitions. Village and weight of the dam had a significant effect on birth weight but not on dystocia. Parity had a significant effect on dystocia score. More abnormal births occurred with AI using exotic bulls. Calves from an abnormal birth were on average more than three kg heavier. First parity births combined with Al with exotic bulls had a particularly high incidence of dystocia. It is concluded that farmers in Pujon can reduce the incidence of dystocia in heifers by using local bulls only.     

Induced Tritrichomonas foetus infection in beef heifers

Four virgin beef heifers were inoculated intravaginally with 7 x 10(6) Tritrichomonas foetus organisms. Protozoal colonization of the vagina, cervix, and uterus developed within the first week after inoculation. Protozoa were no longer detected in secretions from these regions at approximately the same time in each heifer. Trichomonads were detected in reproductive tract secretions for 13 to 28 weeks. Eight weeks after clearance of trichomonads from the reproductive tract, a second infection was established in 2 of the 4 heifers by intravaginal inoculation of T foetus. The second infections were maintained for up to 4 weeks. The diagnostic sensitivity of wet-mount examination of the reproductive tract secretions was 30%, compared with 78% for culture of trichomonads in secretions. Collection and culturing of specimens of cervical and vaginal mucus provided the most reliable method for diagnosis of trichomoniasis during induced infection of heifers.     

Effects of long-term estrogen implants in beef heifers

Crossbred beef heifers (n = 78) were assigned randomly to one of three treatments. Heifers received either no implant, one estradiol-releasing implant (Compudose), or two estradiol-releasing implants. Heifers were implanted at birth and then reimplanted every 150 d. Calves were maintained with the cows until weaning at approximately 200 d of age. Heifers were placed in the feedlot as one group and fed a growing diet for 56 d. Following the growing phase, heifers were segregated into their respective treatment groups and fed until selected by industry buyers for harvest. Beginning at 1 yr of age and continuing every 14 d until puberty or harvest, heifers were palpated per rectum, and blood samples were collected for determination of ovarian activity and attainment of puberty. Serum progesterone of > or =1 ng/mL and(or) palpation of a detectable corpus luteum were criteria of puberty. At weaning and again at harvest, an x-ray was taken of the left front leg of six heifers selected randomly from each group. Metacarpal bones III and IV from the same animals were collected at harvest and transected for determination of epiphyseal plate closure. The x-ray scores and the actual measurements had a correlation of .94. Epiphyseal plate closure occurred in a dose-related manner, with heifers on the higher dose of estrogen having earlier plate closure than heifers on the lower dose. At harvest, reproductive tissues and carcass data were collected for all heifers. Eighteen of 25 untreated control heifers (P < .05), 6 of 26 heifers treated with one implant, and 2 of 26 heifers treated with two implants attained puberty by the end of the experiment. No differences (P > .10) were detected among treatment groups for carcass traits. These data suggest that early and continuous treatment of heifers with estradiol implants can retard reproductive function.     

Serum copper concentrations in beef cows and heifers

OBJECTIVE: To characterize serum copper status of cows and heifers in beef cow-calf herds throughout the United States and to evaluate use of copper supplements in those herds. DESIGN: Cross-sectional survey. ANIMALS: 2,007 cows and heifers from 256 herds in 18 states. PROCEDURES: Producers participating in a health and management survey conducted as part of the National Animal Health Monitoring System voluntarily allowed serum samples to be obtained from cows and heifers for determination of copper concentration. Results were categorized as deficient, marginally deficient, or adequate. The proportion of cattle and herds (on the basis of mean value of the tested cattle) in each category was determined. Copper concentrations were compared between herds that reportedly used copper supplements and those that did not. RESULTS: Overall, 34 of 2,007 (1.7%) cows and heifers were deficient in copper, and 781 (38.9%) were marginally deficient. In each region, at least a third of the cattle were deficient or marginally deficient. For herds, 92 of 256 (35.9%) were marginally deficient, and 22 (0.8%) were deficient. Approximately half of the producers reported use of copper supplements, but a sizeable proportion of those producers' cattle and herds were classified as marginally deficient or deficient. CONCLUSIONS AND CLINICAL RELEVANCE: Copper deficiency is not restricted to a single geographic region of the United States. Copper deficiency can persist despite reported use of supplements by producers. Veterinarians dealing with beef cow-calf herds that have problems consistent with copper deficiency should not rule out copper deficiency solely on the basis of geographic region or reported use of copper supplements for the herd.     

Effect of antiparasitic treatment in beef replacement heifers

Two studies were conducted in western Canada to evaluate the impact of antiparasitic treatment on weight gain and reproductive performance in beef replacement heifers from weaning to first breeding. Treatment of heifers at weaning with ivermectin increased the rate of weight gain in comparison to treatment with fenthion. The feed efficiency of ivermectin-treated animals was also significantly better than those treated with fenthion. Increased weight was associated with an increased number of animals in estrus at the end of the feeding period for heifers receiving ivermectin. We concluded that treatment with ivermectin improved feed efficiency and weight gain in heifers from weaning to breeding. In turn, this weight gain appeared to be associated with an increased number of heifers in estrus.     

Progestin and prostaglandin for estrous synchronization in beef heifers

Seventy-eight Simmental-Angus-Hereford crossbred yearling heifers, in 1983, and 99 similar heifers, in 1984, were used to compare two estrous synchrony regimens. One treatment group (SMB) was synchronized using the commercially available Syncro-Mate-B procedure, which involved placing a norgestomet implant in the ear for 9 d and giving an injection of norgestomet and estradiol valerate at the time of implantation. A second group (PR + PG) was given a norgestomet implant (PR) for 7 d and a 5-mg injection of alfaprostol (PG) at implant removal. Percentage of heifers cycling during the synchronization period and percent conceiving in 5 d or 30 d were not different (P greater than .10) due to treatment. The interval from implant removal to onset of behavioral estrus was shorter (P less than .01) for the heifers treated with SMB than for the heifers treated with PR + PG (42.8 vs 58.0 h). The group treated with SMB had a more uniform synchrony of estrus than the group treated with PR + PG. The effect of day of the estrous cycle at implantation on hours to estrus after implant removal was determined by a regression analysis, which showed a linear response for the SMB group with a slope of .78 (P = .09); the PR + PG group regression was cubic (P less than .01); this also indicated a more uniform response by the SMB group. These results indicate that the combination of norgestomet and alfaprostol produced more variation in interval from treatment to estrus than the Syncro-Mate-B procedure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Micronutrients affecting adipogenesis in beef cattle

Beef marbling is an important trait of meat quality and beef marbling influences the tenderness and flavor of beef, which contributes directly to the value of beef especially in the Japanese market. The lipid content of beef depends on the strain, sex, diet and fattening period of the animal. Japanese Black cattle (Wagyu) are well‐known for their ability to produce marbling beef and this is a popular strain in Japan. The development of beef marbling was closely associated with an increase in the number of adipocytes, that is, adipocyte differentiation in the skeletal muscle. This review article describes our experiment and related reports on micronutrients, especially vitamins and minerals, affecting adipogenesis in beef cattle. We pursue the possibility that manipulating the level of dietary micronutrients may become a new technique to promote beef marbling.     

影响肉牛肌内脂肪沉积的遗传、管理和营养因素

肌内脂肪在骨骼肌中的含量包括长背肌,也称为大理石花纹脂肪,是决定牛肉质量最重要的因素之一。基因、品种、管理和营养影响肌内脂肪沉积。在此,本文综述了影响肌内脂肪沉积的遗传因素(品种、性别差异和遗传力)和管理因素。阉割公牛会增加大多数品种牛的肌内脂肪沉积。本文还综述了断奶日龄、阉割、屠宰体重、年龄和环境条件等因素对肌内脂肪沉积的影响。营养因素包括脂肪代谢,饲料消化、吸收,葡萄糖、淀粉的有效性,维生素水平。因此,根据消费者对牛肉的偏好,可能需要多种策略的组合来调控肌内脂肪的沉积。     

Factors affecting pregnancy rate to estrous synchronization and fixed-time artificial insemination in beef cattle

Application of AI in extensive beef cattle production would be facilitated by protocols that effectively synchronize ovarian follicular development and ovulation to enable fixed-time AI (TAI). The objectives were to determine whether use of a controlled internal drug release (CIDR) device to administer progesterone in a GnRH-based estrous synchronization protocol would optimize blood progesterone concentrations, improve synchronization of follicular development and estrus, and increase pregnancy rates to TAI in beef cows. Beef cows (n = 1,240) in 6 locations within the US Meat Animal Research Center received 1 of 2 treatments: 1)?an injection of GnRH [100 μg intramuscularly (i.m.)] followed by PGF(2α) (PGF; 25 mg i.m.) 7 d later (CO-Synch), or 2) CO-Synch plus a CIDR during the 7 d between GnRH and PGF injections (CO-Synch + CIDR). Cows received TAI and GnRH (100 μg i.m.) at 60 h after PGF. Progesterone was measured by RIA in blood samples collected 2 wk before and at initiation of treatment (d 0) and at PGF injection (d 7). Estrous behavior was monitored by Estrotect Heat Detectors. Pregnancy was diagnosed by ultrasonography 72 to 77 d after TAI. Plasma progesterone concentrations did not differ (P > 0.10) between synchronization protocols at first GnRH injection (d 0), but progesterone was greater (P < 0.01) at PGF injection (d 7) in cows receiving CO-Synch + CIDR vs. CO-Synch as a result of fewer CIDR-treated cows having progesterone ≤1 ng/mL at PGF (10.7 vs. 29.6%, respectively). A greater (P < 0.01) proportion of CO-Synch + CIDR vs. CO-Synch cows were detected in estrus within 60 h after PGF (66.7 vs. 57.8 ± 2.6%, respectively) and a greater (P < 0.01) proportion were pregnant to TAI (54.6 vs. 44.3 ± 2.6%, respectively). For both synchronization protocols, cows expressing estrus within 60 h before TAI had a greater pregnancy rate than cows without estrus. For cows with plasma progesterone ≤1 ng/mL at PGF injection, CO-Synch + CIDR increased pregnancy rate (65.2 ± 5.9 vs. 30.8 ± 3.4% with vs. without CIDR), whereas pregnancy rates did not differ (P > 0.10) between protocols (52.1 ± 2.1 vs. 50.0 ± 2.4%, respectively) when progesterone was >1 ng/mL (treatment × progesterone; P < 0.01). Inclusion of a CIDR in the synchronization protocol increased plasma progesterone concentration, proportion of cows detected in estrus, and pregnancy rate; however, the increase in pregnancy rate from inclusion of the CIDR was primarily in cows with decreasing or low endogenous progesterone secretion during treatment.     

Performance of beef heifers supplemented with sodium lasalocid

This study was conducted on 78 13-month-old crossbred beef heifers that weighed 215 kg in Southern Rio Grande do Sul (RS) State, Brazil. We evaluated the performance of beef heifers that were reared in a pasture system that received a mineral supplement energy-type protein with added sodium lasalocid (LAS). The heifers were randomly and uniformly divided into 2 groups, with 39 animals in each group. One group of animals received a mineral supplement energy-type protein without sodium lasalocid (CON), and the other group received a mineral supplement energy-type protein with added LAS. The mean feed intake, the body weight (BW), the average daily gain (ADG), the body condition score (BCS), and ovarian cyclicity were recorded, and economic parameters were calculated. No differences in supplement intake were observed between the groups, which ensures adequate intake of the other components of the mineral mixture, which are part of the nutritional requirements for the production process. Similarly, no difference in the ADG was observed between treatments. We observed that the heifers in the LAS group had a higher BW gain (51 kg) that the CON heifers (40 kg; P?<?0.05). In addition, LAS-supplemented heifers had a higher BCS (3.53) than CON heifers (3.38) at the end of the experiment (P?<?0.05). The heifers supplemented with LAS had a higher profitability than the CON heifers, even with the higher cost of the supplement containing LAS; this effect was due to the higher live BW at the end of the study. We concluded that the administration of a mineral supplement energy-type protein with added LAS has beneficial effects on beef heifers in terms of production and economic feasibility.     

An abattoir survey of reproductive organ abnormalities in beef heifers

During the period from April 1984 to March 1985, a survey of abnormalities in beef heifer reproductive tracts was performed in an Ontario abattoir. Data concerning both pregnancy and gross pathology were collected on 5800 heifers. Pregnancy was found in 382 (6.6%) of the heifers examined. Various abnormalities were detected in 1499 (27.7%) of the remaining 5418 heifers. Cystic ovaries were found in 807 nonpregnant heifers (14.9%) and ovarian bursal adhesions and mucometra affected 5.4% and 5.0% of heifers, respectively. The prevalence of cystic ovaries and mucometrs was higher (p<0.05) in heifers exposed to melengestrol acetate.