Effects of porcine relaxin on induced parturition in beef heifers

Two-year-old crossbred beef heifers were used to test the effects of porcine relaxin (pRelaxin) alone, or in combination with dexamethasone, on the induction of parturition, the incidence of dystocia, and retained placentas. Effects of treatment on pelvic area, postpartum interval, milk production, colostrum quality, calf birth weight, calf vigor, and calf performance were also evaluated. On Day 275 of gestation, heifers from two fetal-sire groups were randomly assigned to one of four groups in a 2 × 2 factorial design and received: no treatment (controls, N = 19), 20 mg of dexamethasone intramuscularly (im) (n = 22), 5 mg of pRelaxin (3,000 U/mg) im (n = 19), or 20 mg of dexamethasone plus 5 mg of pRelaxin (n = 17). Length of gestation (in days) was less (P < 0.05) in heifers treated with dexamethasone (279.8 ± 1.0) than in controls (286.6 ± 0.9), but was not influenced (P > 0.05) by treatment with pRelaxin. The incidence of retained placentas in heifers treated only with dexamethasone (27.3%) was not reduced by concomitant treatment with pRelaxin (35.3%). Retained placentas were not observed in any control heifers and in only one heifer (5.2%) treated solely with pRelaxin. Ease of calving (1 = unassisted, 5 = abnormal presentation) was not influenced by treatment (P > 0.05), even though birth weights (in kilograms) of calves from heifers treated with dexamethasone (36.4 ± 0.8) were less (P < .01) than those of calves from nondexamethasone-treated heifers (39.2 ± 0.8). Dexamethasone tended to reduce (P < 0.07) calf vigor (1 = healthy and strong, 5 = dead on arrival; 1.48 ± 0.11 vs. 1.18 ± 0.11), but was not (P > 0.05) influenced by pRelaxin. The duration of the postpartum anestrous interval (73.1 ± 1.8 d across groups) and pelvic areas following treatment and parturition were not influenced (P > 0.05) by dexamethasone or pRelaxin. Although determinants of colostrum quality (P < 0.01) and quantity (P < 0.08) of milk produced were influenced by dexamethasone, adjusted 205-d weights of calves did not differ (P > 0.05) among groups. In conclusion, treatment with pRelaxin alone failed to induce parturition or, when combined with dexamethasone, to reduce the incidence of retained placentas.     

Factors influencing time of parturition in range beef cattle

A total of 2434 calving records from seven calving seasons were analyzed by the least-squares and chi-square procedures to study the influences of breeding group, age of dam, sex and birth weight of calf and dam weight at calving on the time of day of parturition. Frequency of day calving (0630 ± 030 to 1900 h) was slightly but not significantly higher than night calving (1900 h to 630 ± 030). The frequency of night calving was higher among heifers compared with the older cows. The cows which calved after May 15 (the last one third period of pregnancy) had higher frequency of day calving compared with those that calved earlier. The frequency of daytime calving was higher among the cows that weighed at most one standard deviation below the average compared to heavier cows of comparable age.     

Influence of feeding regime on timing of parturition in beef cattle and the relationship of vaginal temperature to parturition

The timing of parturition was recorded for a total of 56 beef cattle (Japanese Black × Holstein Friesian) on different dietary treatments. The rate of calving during daylight hours in cows night‐fed (18.00 hours) with a roughage diet was significantly higher than that in cows night‐fed with a high concentrate diet (79.2% vs 38.5%, P < 0.05). Subsequently, the vaginal temperature (VT) of these cows was analyzed using a cosinor method. When the feeding schedule was changed from twice daily (08.30 and 15.30 hours) to night feeding, the periodicity, the acrophase and the bathyphase, which were the parameters of the cosine curve, were unstable from the first day of night feeding until after day 6 (P < 0.05). Prior to parturition, the midline‐estimating statistic of rhythm (MESOR) and the amplitude for the cows that were fed a high‐roughage diet at night and that calved at night‐time were lower and larger, respectively, than that for the other treatments (P < 0.01). Based on these results, the time of parturition in most of the beef cows was influenced by feeding time and diet composition. Those cows that calved at night‐time in spite of night feeding had lower vaginal temperatures.     

The economy of induced early parturition in New Zealand dairy herds

A breakeven analysis suggests that the economy of inducing cows to calve prematurely is precariously balanced. The analysis is based on data from recent New Zealand publications and on replies to a questionnaire sent to participants in a previously reported induction trial. It suggests that the extra cost per induction is $18.60, that the cost saved is $23.40 and that the income lost $28.80. This implies that extra returns have to be about $24.00 to achieve a nil balance and it is suggested that this might be just possible during the first lactation after induction. Any profit will have to come from advantages beyond the first year. The questionnaire data indicate that about 2/3 of induced cows are likely to provide such advantages, but that 1/3 might cause further losses. It is recommended that the technique of inducing dairy cows to calve prematurely be judiciously employed, mainly in emergency, on young and healthy cows only.     

科尔沁肉牛早期补饲饲养模式试验研究

[目的]通过试验探究科尔沁肉牛犊牛最佳的饲养模式,为后续科尔沁肉牛早期补饲的推广和普及提供理论支持。[方法]选取体型相近,初生体重在34～50 kg之间健康的科尔沁肉牛犊牛60头,分为对照组、补饲组1、补饲组2,每组20头,补饲组按试验方案进行早期补饲,对照组按传统饲养模式饲养,对比6月龄各项数据及试验牛母牛产后发情情况,进行分析总结。[结果]补饲组与对照组相比,犊牛生长发育效果差异显著,试验母牛产后恢复明显加快,产后90 d内发情母牛占比显著提高。[结论]科尔沁肉牛犊牛早期补饲更利于犊牛后期生长发育,促进母牛早发情提高繁殖能力,结合数据分析得出早期补饲至6月龄是更为适合科尔沁肉牛犊牛的饲养模式。     

Uterine diseases in cattle after parturition

Bacterial contamination of the uterine lumen is common in cattle after parturition, often leading to infection and uterine disease. Clinical disease can be diagnosed and scored by examination of the vaginal mucus, which reflects the presence of pathogenic bacteria such as Escherichia coli and Arcanobacterium pyogenes. Viruses may also cause uterine disease and bovine herpesvirus 4 (BoHV-4) is tropic for endometrial cells, causing a rapid cytopathic effect. The elimination of pathogens by the innate immune system is dependent on pattern recognition receptors binding pathogen-associated molecules. Uterine epithelial and stromal cells express receptors such as Toll-like Receptor 4 that binds E. coli lipopolysaccharide. The infertility associated with uterine disease is caused by damage to the endometrium and disruption of ovarian cyclic activity. Bacteria modulate endometrial prostaglandin secretion, and perturb ovarian follicle growth and function. Understanding the molecular basis of uterine disease will lead to novel approaches to treating infertility.     

肉牛同期发情效果影响因素的研究

[目的]为了研究同期发情处理方法、繁殖状况、品种、体重等对肉牛同期发情效果的影响,[方法]选择140头不同繁殖状况、品种、体重的肉牛,随机分为3组,分别采用CIDR+第10天肌注PMSG+第11天肌注PGF_2α（埋栓Ⅰ组）、CIDR+第9天肌注PMSG+第11天肌注PGF_2α（埋栓Ⅱ组）、肌注PGF_2α+PMSG(PGF_2α组)的方法进行同期发情处理。[结果]3种不同处理方法相比,PGF_2α组发情率为87.10%,埋栓Ⅰ组、Ⅱ组母牛发情率分别为97.83%、98.41%,显著高于PGF_2α组（P<0.05）;PGF_2α组处理牛受胎率为83.87%,埋栓Ⅰ组、Ⅱ组处理牛受胎率分别为89.13%、84.13%,高于PGF_2α组,但差异不显著（P>0.05）;育成牛与经产牛发情时间相比,埋栓组12～24 h内出现发情症状的经产牛占比为27.27%,育成牛占比为60%,显著高于经产牛（P<0.05）,2...     

Maternal periconceptual nutrition,early pregnancy,and developmental outcomes in beef cattle

The focus of this review is maternal nutrition during the periconceptual period and offspring developmental outcomes in beef cattle, with an emphasis on the first 50 d of gestation, which represents the embryonic period. Animal agriculture in general, and specifically the beef cattle industry, currently faces immense challenges. The world needs to significantly increase its output of animal food products by 2050 and beyond to meet the food security and agricultural sustainability needs of the rapidly growing human population. Consequently, efficient and sustainable approaches to livestock production are essential. Maternal nutritional status is a major factor that leads to developmental programming of offspring outcomes. Developmental programming refers to the influence of pre-and postnatal factors, such as inappropriate maternal nutrition, that affect growth and development and result in long-term consequences for health and productivity of the offspring. In this review, we discuss recent studies in which we and others have addressed the questions, “Is development programmed periconceptually?” and, if so, “Does it matter practically to the offspring in production settings?” The reviewed studies have demonstrated that the periconceptual period is important not only for pregnancy establishment but also may be a critical period during which fetal, placental, and potentially postnatal development and function are programmed. The evidence for fetal and placental programming during the periconceptual period is strong and implies that research efforts to mitigate the negative and foster the positive benefits of developmental programming need to include robust investigative efforts during the periconceptual period to better understand the implications for life-long health and productivity.     

Maternal behavior of beef cows at parturition

Over an 11-yr period maternal behavior, calf birth weight and calf condition were recorded within 24 h for 2,684 parturitions. Maternal behavior was rated on a scale from 1 to 11, where 1 indicated extreme aggressiveness and 11 indicated no maternal attentiveness. Birth condition was rated on a scale from 1 to 9, with 9 being fattest and 1 thinnest. Respective breed means of Hereford, Angus, Charolais and Red POll were 6.2, 5.3, 6.0, and 5.7 for maternal behavior rating; 30.6, 27.3, 39.2 and 32.6 kg for birth weight, and 5.5, 4.7, 5.6 and 5.5 for birth condition. Heritability estimates for maternal rating, birth weight and birth condition were .06 +/- .01, .48 +/- .02 and .19 +/- .01, respectively. Genetic correlations between maternal rating and birth weight and condition were .04 +/- .05 and -.02 +/- .06, respectively. These results suggest that, in the population of cows studied, nongenetic influences were the primary cause of differences in aggressiveness of cows at parturition.     

Effects of calpastatin and micro-calpain markers in beef cattle on tenderness traits

The objective of this study was to assess the association of single nucleotide polymorphisms (SNP) developed at the calpastatin (CAST) and mu-calpain (CAPN1) genes with meat tenderness and palatability traits in populations with diverse genetic backgrounds. Three populations were used in the study. One population consisted of Bos taurus that included crossbred animals derived from Hereford, Angus, Red Angus, Limousin, Charolais, Gelbvieh, and Simmental (GPE7; n = 539). Another population consisted of Bos taurus with Bos indicus influence, including crossbred animals from Hereford, Angus, Brangus, Beefmaster, Bonsmara, and Romosinuano (GPE8; n = 580). The third population was Bos indicus and consisted of purebred Brahman (STARS; n = 444). Traits evaluated were meat tenderness measured as Warner-Bratzler shear force (WBSF; kg) at 14 d postmortem, and traits evaluated by trained sensory panels that included tenderness score, juiciness, and flavor intensity. A SNP at the CAST gene had a significant (P < 0.003) effect on WBSF and tenderness score in the GPE7 and GPE8 populations. Animals inheriting the TT genotype at CAST had meat that was more tender than those inheriting the CC genotype. The marker at the CAPN1 gene was significant (P < 0.03) for tenderness score in GPE7 and GPE8. Animals inheriting the CC genotype at CAPN1 had meat that was more tender than those inheriting the TT genotype. Markers at the CAST and CAPN1 genes were associated with flavor intensity in the GPE8 population. Animals inheriting the CC genotype at CAST and the TT genotype at CAPN1 produced steaks with an intense flavor when compared with the other genotypes. An interaction between CAST and CAPN1 was detected (P < 0.05) for WBSF on GPE8. The statistical significance of the interaction is questionable because of the limited number of observations in some cells. Markers developed at the CAST and CAPN1 genes are suitable for use in identifying animals with the genetic potential to produce meat that is more tender.     

粮对肉牛小肠pH值及胰蛋白酶话性的影响

对肉牛饲喂不同日粮玉米秸,５０％玉米秸加５０％精料后小肠不同部位（十二指肠、空肠和回肠）ｐＨ值及胰蛋白酶活性进行了测定,结果表明：肉牛小肠不同部位的ｐＨ值不同,回肠ｐＨ值高于空肠,回肠和空肠ｐＨ值显著高于十二指肠（Ｐ〈０．０５）,饲喂５０％玉米秸加５０％精料日粮的牛小肠ｐＨ值低于喂单一玉米秸日粮;肉牛小肠不同部位的胰蛋白酶活性不同,空肠高于回肠,空肠和回肠显著高于十二指肠（Ｐ〈０．０５）,饲喂５０