Determination of reference intervals for metabolic profile of Hanwoo cows at early,middle and late gestation periods

Background

Metabolic profile was initially designed as a presymptomatic diagnostic aid based on statistical analyses of blood metabolites to provide an early warning of certain types of metabolic disorder. However, there is little metabolic profile data available about Korean Hanwoo cows. Therefore, this study aimed to determine the reference intervals of metabolic profile for Korean Hanwoo cows.

Methods

Healthy animals (2,205) were selected and divided into early (day 1 to 95), middle (day 96 to 190) and late (day 191 to 285) period according to their gestating period. Metabolic profile including total protein (TP), albumin (Alb), urea (UREA), glucose (Glu), total cholesterol (T-Cho), long-chain fatty acid (LCFA), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGT), creatinine (Crea), calcium (Ca), inorganic phosphorous (iP) and magnesium (Mg) were analyzed using a TBA-40FR automatic biochemical analyzer. The data of Korean Hanwoo cows were then compared to those of the Japanese Wagyu cows.

Results

Most of the data of the Korean Hanwoo cows were relatively higher than those of Japanese Wagyu cows, with the exception of Glu and GGT. This may indicate that the nutritional level of feed for the Korean Hanwoo cows was higher than that of the Japanese Wagyu cows because of the different feeding system. In particular, relatively higher levels of UREA and LCFA were observed in the Korean Hanwoo cows, and this may also contribute to the low reproduction efficiency.

Conclusions

These findings may provide some theoretical basis for understanding the reproductive and feeding situation of Korean Hanwoo cows.     

一起群发性奶牛尿素中毒的临床研究

2004年南京某奶牛公寓由于饲养户在奶牛饲料中添加尿素方法不当,引起群发性尿素中毒。该牛群共有奶牛87头,发病64头,药物治疗56头,治愈54头,死亡10头,均为成母牛。作者调查了发病牛群的病史、临床症状、病理变化、治疗情况,对中毒奶牛的血液进行生化分析,并与正常奶牛比较,结果血清谷草转氨酶(AST)、γ-谷氨酰转移酶(GGT)、碱性磷酸酶(ALP)、磷酸肌酸激酶(CK)、磷酸肌酸激酶同工酶(CK-MB)、肌酐(CRE)、尿素氮(UN)、葡萄糖(GLU)、乳酸脱氢酶(LDH-L)等差异极显著(P<0·01),尿素(UREA)、血清K等差异显著(P<0·05),这些指标活性升高说明病牛心肌、胃肠平滑肌、肝肾等存在与病死牛的病理变化相一致的损伤。     

Cow level sampling factors affecting analysis and interpretation of milk urea concentrations in 2 dairy herds.

The goals of this study were to determine the influence of the variations among udder quarters, the somatic cell count, the time of sampling during the day, sample conservation, and centrifugation on milk urea (UREA) concentrations, and to propose a sample collection procedure for herds that are not on a Dairy Herd Improvement (DHI) program. Forty cows from 2 herds with different feeding practices were randomly selected. The quarter sampled and the somatic cell count did not significantly influence UREA concentrations. Milk urea concentrations were highest in the morning. The diurnal pattern was not influenced by intrinsic factors like parity, days postpartum, or daily milk yield. The UREA concentrations were significantly higher after refrigeration for one week (mean UREA change = +0.41 +/- 0.24 mmol/L, P = 0.0001) and freezing for one month (mean UREA change = +1.52 +/- 1.25 mmol/L, P = 0.0001). Urea concentrations were slightly higher in lactoserum than in whole milk (mean UREA difference = +0.17 +/- 0.24 mmol/L, P = 0.0001). Although this study included only 2 herds and does not allow extrapolation, differences were found in the diurnal pattern of UREA in these 2 herds, which possibly reflect differences in feeding strategy. With consideration of these results, a 6-point sampling procedure for herds that are not on a DHI program is proposed.     

Adiposity, fatty acid composition, and delta-9 desaturase activity during growth in beef cattle

Oleic acid (18:1n‐9) is the most abundant fatty acid in bovine adipose tissue. Because most of the lipid in bovine muscle is contributed by intramuscular adipocytes, oleic acid also is the predominant fatty acid in beef. In many species, the concentration of oleic acid in adipose tissue is dictated by the average concentration of oleic acid in the diet, but in ruminant species such as beef cattle, oleic acid is hydrogenated largely to stearic acid by ruminal microorganisms. In these species, the concentration of oleic acid in adipose tissue is dependent upon the activity of Δ⁹ desaturase, encoded by the stearoyl coenzyme A desaturase (SCD) gene. Expression of the SCD gene is essential for bovine preadipocyte differentiation, and desaturase gene expression and catalytic activity increase dramatically as adipose tissue mass increases after weaning. Feeding a hay‐based diet to American Wagyu steers to a typical Japanese bodyweight endpoint (650 kg) markedly stimulated desaturase enzyme activity as well as the accumulation of both oleic acid and intramuscular lipid, but the increase in oleic acid and intramuscular lipid was much less in hay‐fed Angus steers. Increasing the concentration of oleic acid improves the palatability and healthiness of beef, and Korean Hanwoo and Japanese Black (and American Wagyu) seem especially well adapted to accumulate oleic acid in their adipose tissue.     

日本和牛胚胎移植的试验研究

[目的]为了在我国引进日本和牛这一高等级肉牛品种并迅速扩大纯种日本和牛的数量.[方法]分别采用CIDR+E2法和两次PGF2α法对胚胎移植受体牛做同期发情处理,采用一步细管法冷冻的日本和牛胚胎进行移植,观察妊娠率.[结果]表明,受体牛经CIDR+E2法和两次PGF2α法处理后12～48 h的发情率分别为82.7%和45.9%,两者之间差异显著(P＜0.05),对90枚日本和牛胚胎进行一步细管法管内解冻,然后给62头CIDR+E2法处理和28头两次PGF2α法处理的受体奶牛移植,受胎率分别为43.5%和42.5%,产犊率分别为40.3%和39.3%,两者之间差异不显著(P＞0.05).[结论]经同期发情处理的受体牛,只要其子宫环境及卵巢黄体发育良好,被移植日本和牛胚胎都能正常妊娠和产犊;用日本和牛胚胎对低产奶牛进行移植,经三代纯化即可获得纯种日本和牛.     

Comparison of plasma metabolite concentrations and enzyme activities in beef cattle raised by different feeding systems in Korea, Japan and New Zealand

Concentrations of metabolites and immunoreactive insulin (IRI) and activities of enzymes related to energy metabolism were measured in plasma of Korean and Japanese beef cattle, which were raised by the indoor feeding system programmed to feed larger amount of roughage in their growing periods and larger amount of concentrate diet in their finishing periods (Japanese feeding system), and grazing New Zealand beef cattle. By the Japanese beef grading system, Korean and Japanese beef cattle showed high beef quality score, average grade 3.3 and 3.6, respectively. The plasma free fatty acid and lactate concentrations and lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and aspartate aminotransferase (AST) activities in Korean beef cattle were significantly higher than those in Japanese beef cattle. The plasma lactate concentration in Korean beef cattle was 8.40 mmol/l, which was similar to the values observed in lactic acidosis. The higher activities of plasma LDH, MDH and AST may indicate slight liver damage by slightly acidotic conditions in Korean beef cattle. New Zealand beef cattle fed on pasture which they harvest by grazing showed significantly lower plasma glucose, cholesterol, lactate and IRI concentrations and enzyme activities than those in Korean and Japanese beef cattle fed on larger amount of concentrate diets. Plasma metabolite concentrations and energy metabolism-related enzyme activities may be good indicators for evaluating metabolic conditions of beef cattle raised by different feeding systems.     

引进日本和牛冻精改良本地黄牛效果观察

[目的]观察日本和牛冻精与不同肉牛品种杂交改良效果.[方法]选择胎次、膘情和年龄接近,健康无病、饲养管理条件基本相同的经产西杂、秦杂、奶杂和本地母牛150头,随分为工、Ⅱ、Ⅲ、Ⅳ和V5组,每组30头.Ⅰ、Ⅱ、Ⅲ、Ⅳ组的120头基础母牛选用日本和牛冻精授配改良,即：日本和牛冻精x;西门塔尔x;本地黄牛杂交组合（简称和西杂组）,日本和牛冻精x;秦川x;本地黄牛杂交组合（简称和秦杂组）,日本和牛冻精x;荷斯坦奶牛x;本地黄牛杂交组合（简称和奶杂组）,日本和牛冻精x;本地黄牛（简称和杂组）,V组为本地黄牛.测量初生、6月龄、12月龄体尺、体重.[结果]表明：在初生、6月龄、12月龄体尺、体重数据中,和秦杂牛组、和西杂牛组、和奶杂牛组和和杂牛组与本地黄牛之间有显著差异（P＜0.05）;和秦杂牛组、和西杂牛组、和奶杂牛组与和杂牛组差异显著（P＜0.05）,与本地黄牛组差异极显著（P＜0.01）.[结论]和秦杂牛、和西杂牛组合可作为本市推广品种.     

产前运动对围产期奶牛生理代谢指标的影响

本试验旨在研究产前运动对围产期奶牛生理代谢指标的影响，为围产期奶牛健康管理提供科学指导和理论依据。试验选取年龄相似，体况评分、胎次和预产期相近的经产荷斯坦奶牛24头，随机分为试验组（TRT组）和对照组（CON组），每组12头，统一饲养管理。于预产期前21 d开始，TRT组奶牛每日09：00和16：00以<3 km/h的速度运动1 h，每头奶牛每日总运动量为（4.0±0.2） km/d；CON组自由活动。分别在预产期前21、7 d、分娩当天及产后7、30 d （分别记为－21、－7、0、+7和+30 d），于晨饲前采集血液，测定血浆中非酯化脂肪酸（NEFA）、β-羟基丁酸（BHBA）、葡萄糖（GLU）、甘油三酯（TG）、胆固醇（CHOL）、肌酐（CREA）及尿素（UREA）浓度。结果显示，试验期间，TRT组血浆NEFA、BHBA浓度与CON组相比均呈下降趋势（0.05<P<0.1），－7 d时TRT组NEFA浓度显著低于CON组（P<0.05）；TRT组血浆GLU浓度变化较CON组平稳，在＋30 d极显著高于CON组（P<0.01）；两组血浆TG浓度均在分娩当天急剧下降，产前血浆TG浓度均极显著高于分娩后各时间点（P<0.01），＋30 d时TRT组极显著高于CON组（P<0.01）；血浆UREA、CREA浓度在两组间无显著差异（P>0.05）。综上，以<3 km/h的速度进行运动（4.0 km/d±0.2 km/d），可有效降低围产期奶牛血浆NEFA和BHBA浓度，缓解能量负平衡（NEB）压力。     

Influence of slaughter weight and sex on yield and quality grades of Hanwoo (Korean native cattle) carcasses

To assess the effects of slaughter weight and sex on APGS (Animal Products Grading Service) quality and APGS yield grade of Korean Hanwoo (n = 20,881) cattle, data were collected from cow, bull, and steer carcasses during a 1-yr period. Factors used to determine quality grade (marbling, meat color, fat color, texture, and overall maturity score) and yield grade (cold carcass weight, adjusted fat thickness, and longissimus muscle area) by the Korean grading system were recorded. Both yield and quality grades were improved (P < 0.01) with heavier slaughter weight, but there was no difference in yield grade for Hanwoo cattle classes heavier than 551 kg (P > 0.01). Longissimus muscle area, adjusted fat thickness, and marbling score increased (P < 0.01) with carcass weight. Bull carcasses showed higher yield but lower quality than those of cows or steers (P < 0.01). The quality grade of steer carcasses was higher (P < 0.01) than that of cow carcasses due to higher marbling scores, lower maturity scores, and heavier carcass weights. Hanwoo carcasses with larger longissimus muscle areas in relation to their carcass weight had lower APGS quality grades. The APGS quality grades were different between yield grade A and B carcasses (P < 0.01), but quality grade was not improved by increased fat thickness beyond the point of yield grade B. Adjusted fat thickness and marbling score showed significant (P < 0.01) differences among all yield grade classes, and this resulted in increased quality grade as yield grade decreased. Adjusted fat thickness showed the strongest correlation (r = -0.63) with yield grade, whereas marbling score had the strongest correlation (r = 0.81) with quality grade. Results showed a negative effect of castration on yield but a positive effect on quality. Also, data showed that Hanwoo carcasses with heavier weights had higher quality grades than those of lighter weight.     

Metabolic profiles in ovulatory and anovulatory primiparous dairy cows during the first follicular wave postpartum

Metabolic hormones affect ovarian function in the cow. However, the relationship between metabolic factors and ovarian function is not clear in the postpartum primiparous cow because they are still growing. The aim of the present study was to investigate in detail the time-dependent profile of the metabolic hormones, metabolites, and milk yields of ovulatory and anovulatory primiparous cows during the first follicular wave postpartum. We used 16 primiparous Holstein cows and obtained blood samples for the profiles of metabolites (glucose; non-esterified fatty acid, NEFA; ketone body; total cholesterol; and aspartate aminotransferase), metabolic hormones (growth hormone, GH; insulin-like growth factor-I, IGF-1; and insulin), and progesterone every other day from 1 to 21 days postpartum. In addition, all ovaries were observed using ultrasound. Dairy milk yield was recorded during the experimental period. In all cows, the first follicular wave postpartum was observed and 6 of the cows ovulated. The plasma glucose (P<0.0001) and IGF-1 (P<0.001) concentrations were lower and the plasma NEFA (P<0.0001) and ketone bodies (P<0.0001) concentrations and daily milk yield (P<0.0001) were higher in the anovulatory cows compared to the ovulatory cows. However, the GH levels, which enhance lipolysis for milk production, insulin and other metabolites did not differ between the two groups. In conclusion, the present study suggests that anovulation of the dominant follicle during the first follicular wave postpartum in primiparous cows is induced by low IGF-1 levels that are similar to those of multiparous cows. In addition, anovulatory cows are likely to mobilize body fat stores for milk production more easily than ovulatory cows.     

Alterations in biochemical profiles and reproduction performance in postpartum dairy cows with metritis

The aim of the present study was to evaluate the biochemical profile and reproductive performance in postpartum dairy cows with clinical metritis. The research was carried out using performed on 213 pluriparous lactating cows from two dairy herds in southeast Brazil. Dairy cows were assigned into a group of healthy cows (n = 147) and cows with metritis (n = 66). Blood samples to assess serum albumin, cholesterol, fibrinogen, calcium, gamma-glutammyltransferase (GGT), aspartate aminotransferase (AST) and β-hydroxybutyrate (BHBA) concentrations were performed on day 8 ± 2 postpartum. Metritic cows had lower (p < .05) serum albumin, cholesterol and calcium concentration, and higher (p < .05) GGT and AST activity, and BHBA and fibrinogen concentrations when compared to the healthy group. The calving-to-conception interval and services per pregnancy were higher in metritic cows (p < .01) than in healthy cows and the conception rate at first service was lower in metric group (p < .01). Variable importance in projection plots demonstrated that cholesterol was the main discriminator between metritic and healthy cows. Our results indicated alterations in the biochemical profile and impaired reproduction performance in metritic cows.     

Influence of feeding methods on blood biochemical parameters of Japanese Black breeding herd

The aim of this study was to investigate the effect of different feeding methods on blood biochemical parameters by using a total of 32 Japanese Black breeding cows. The diet (silage) was distributed at a rough estimate for 18 days (FN period), and stanchions were not used in this period. After the FN period, the cows were separated in stanchions for feeding and were fed specified amount of silage by using scales on a feeder wagon, which was determined according to the diet formulation and average body weight of cows, for 30 days (FW period). On the last day of the two experiment periods, the body weight of all cows was recorded and blood samples were collected from 10 randomly selected cows. β‐hydroxybutyric acid and albumin (Alb) levels were significantly higher after the FW period than after FN period. The variation of glucose, Alb, calcium and lactic acid was significantly smaller after the FW period. Several blood parameters of the FW period were approximately the appropriate range of a Japanese Black breeding herd in the dry period. Our results suggest that the feeding method by use of a stanchion and proper diet formulation affects blood biochemical parameters and improves nutritional conditions for breeding cows.     

日粮添加不同比例的中短链和长链脂肪酸对奶牛免疫功能的影响

为探讨不同比例的中短链和长链脂肪酸混合物对奶牛免疫功能的影响,试验选用72头产奶量、胎次及泌乳日龄相近的中国荷斯坦奶牛,按随机区组试验设计,分为对照组和5个处理组,对照组饲喂基础日粮,处理组在基础日粮上分别添加400 g/d 长链脂肪酸(LCFA,A组)、80 g/d中短链脂肪酸(SMCFA)+320 g/d LCFA(B组)、400 g/d 黄油(C组)、240 g/d SMCFA+160 g/d LCFA(D组)及400 g/d SMCFA(E组)。试验期为63 d,第1周为预试期,试验期最后1 d采集血液样品,用于测定血清中免疫球蛋白及细胞因子的含量。结果显示,日粮添加不同比例的中短链和长链脂肪酸对奶牛血清中免疫球蛋白M(IgM)及前列腺素(PGE₂)的含量没有显著影响(P＞0.05);A组免疫球蛋白A(IgA)的含量显著高于B、E组(P＜0.05),B、D组免疫球蛋白G(IgG)的含量显著高于其余4组(P＜0.05)。日粮中添加脂肪酸均能提高奶牛血清中IL-4及IL-10的含量,尤其是D组,增加效果极显著(P＜0.01)。因此,添加240 g/d SMCFA 和160 g/d LCFA更能提高泌乳中期奶牛的免疫性能。     

Immune-metabolic-inflammatory markers in Holstein cows exposed to a nutritional and environmental stressing challenge

Dairy cows are exposed to multiple stressors during the productive cycle, such as metabolic challenges, overcrowding, grouping change, environmental stress and dietary errors. Thus, it is essential to study reliable markers able to detect stress conditions in dairy farms. This study evaluates dairy cows' immunologic and metabolic markers after the sudden and combined exposition to a high-grain diet (75% concentrates) and the abrupt change of the housing system (from free stall to tie stall). A group of twenty-four Holstein cows were enrolled in a challenge study of 28 days duration. Several immunological and metabolic blood markers were evaluated over the trial. Blood samples were taken at day 0 (normal value) and day 1, 3, 7, 14, 21, and 28 (challenge). Data were submitted to a mixed model for repeated measures, including time as fixed and cows as random effects. The nutritional and environmental challenge had heavy effects on animal welfare and cows responded with a dramatic rumination drop. Our results suggest that the most responsive markers after abiotic stressors in cows were as follows: Serum Amyloid A and ROM in the acute response; Ceruloplasmin and GGT in the mid acute and Albumin, Paroxonase and FRAP in the chronic phase. Serum Amyloid A, Ceruloplasmin, Paraoxonase, GGT and ROM resulted as positive phase proteins, while, Albumin and FRAP resulted as negative phase proteins. Preliminary obtained results could concur to develop strategies able to mitigate stressor effects; moreover, the proposed design can be used as a model to test stress nutritional modulators.     

Differences among Wagyu sires for USDA carcass traits and palatability attributes of cooked ribeye steaks

The objective of this experiment was to evaluate the effects of various Wagyu sires on carcass quality traits and palatability attributes of cooked ribeye steaks. Wagyu sires were used and grouped as Old (n = 6) or New (n = 2) sires, based on the chronological order in which they were imported into the United States. One hundred thirteen F1 heifer and steer calves sired by Wagyu bulls out of three different sources of cows were fed a backgrounding diet for 112 d consisting of an 80:20 ratio of roughage:concentrate then grazed on a mixture of orchardgrass and bluegrass pasture for 84 d and finished on a 10:90 ratio of roughage:concentrate diet for 231 d in a feedlot. Progeny from New sires had larger (P < .05) ribeye areas, higher (P < .05) marbling scores, and lower (P < .05) maturity scores than progeny from Old sires. Marbling was positively correlated (P < .05) to brightness (r = .56), texture (r = .60), and fat luster (r = .38). Progeny of New sires had lower shear force values (P < .05) than progeny of Old sires. These results indicate the superiority of New Wagyu sires to produce progeny with more marbling, lower shear force values, and larger ribeye areas than Old Wagyu sires. Furthermore, there are substantial differences between Wagyu sires for carcass quality traits and palatability attributes.     

Use of bovine somatotropin at the time of surgery for left displacement of the abomasum in dairy cows. Minnesota Dairy Practitioners Study Group

OBJECTIVE: To evaluate the effect of a single dose of recombinant bovine somatotropin (bST) on certain metabolic values, health, and milk production of dairy cows undergoing surgery for left displacement of the abomasum. DESIGN: Blinded clinical trial. ANIMALS: 413 cows with left displacement of the abomasum. PROCEDURE: A single 500-mg dose of bST was administered to dairy cows following surgery in field practice conditions for left displacement of the abomasum. A placebo of the same carrier without bST was administered to control cows in this blinded study. Metabolic and production responses in a short-term follow-up period were measured. RESULTS: Blood glucose concentrations in cows 3 to 5 days after surgery were statistically higher for treated cows than for control cows. A higher proportion of treated cows had improved urine ketone test results than did controls. Significant differences in other metabolic values, health, and milk production were not detected. CLINICAL IMPLICATIONS: Treatment of metabolically compromised cows with bST may have some positive effects, but further investigation is needed to confirm therapeutic value.     

Effect of energy density in the diet and milking frequency on hepatic long chain fatty acid oxidation in early lactating dairy cows

The objective of this study was to examine the effects of diet energy density (high versus low) and increased milk yield, induced by increased milking frequency (two versus three times daily), on the hepatic status of triacylglycerol (TAG) and glycogen content and hepatic long chain fatty acid (LCFA) oxidation capacity in early lactation in a 2 x 2 factorial design. Forty multiparous Danish-Holstein dairy cows were used from 8 weeks before to 8 weeks after calving. Liver biopsies and blood samples were taken in weeks -2, 2, and 7 from calving. The cows fed the high energy density diet, compared with the cows fed the low energy density diet, had an 18 and 28% higher milk production and net energy intake, respectively. Milk yield was increased by 10% when the cows were milked three times compared with twice daily. Complete (CO2 production) and incomplete (ketone body production) LCFA oxidation capacity in the liver were 35 and 32% higher, respectively, and liver TAG content was 48% lower for the cows fed the high energy density diet compared with the low energy density diet. Overall there was no effect of milking frequency on liver parameters. However, a significant interaction between diet and milking frequency showed that the cows milked three times daily and fed the low energy density diet had the lowest liver LCFA oxidation (CO2 and ketone body) capacity. Furthermore, these cows had the numerically highest liver TAG content. The results for liver LCFA metabolism are discussed in relation to the plasma concentration of metabolites and insulin. In conclusion, cows in early lactation given a high energy density diet will, in general, have a lower risk of high TAG infiltration in the liver.     

Low Incidence of an Altered Endometrial Epidermal Growth Factor (EGF) Profile in Repeat Breeder Holstein Heifers and Differential Effect of Parity on the EGF Profile Between Fertile Holstein (Dairy) and Japanese Black (Beef) Cattle

A high incidence (about 70%) of alteration in endometrial epidermal growth factor (EGF) profile, i.e., loss of 2 peaks on days 2–4 and 13–14, has been linked to a reduced fertility in multiparous repeat breeder Holstein cows. However, the EGF profile in Holstein heifers and other breeds (types) of cattle has not been investigated. In study 1, EGF concentrations were determined using endometrial tissues obtained by biopsy on days 3, 7 and 14 from 84 fertile Holstein heifers to obtain a normal range and 53 repeat breeder Holstein heifers to estimate incidence of alterations in the EGF profile. In repeat breeder heifers, EGF concentrations were similar to fertile controls on 3 days and five animals (9.4%) had an altered EGF profile with EGF concentrations below the normal range on days 3 and 14. In study 2, EGF concentrations on day 3 were repeatedly examined from the nulliparous period to the third postpartum period in 28 Holstein (dairy) and 47 Japanese Black (beef) cattle. The effect of parity on EGF concentrations on day 3 was different between Holstein and Japanese Black cattle. In Japanese Black cows, the EGF concentrations were consistently high throughout the study period, while in Holstein cows, the EGF concentrations decreased after the second calving. In conclusion, unlike multiparous repeat breeder Holstein cows, an altered EGF profile may not be a major cause of repeat breeding in Holstein heifers, and the peak EGF concentrations around day 3 may decrease even in fertile populations of multiparous dairy cows, but not in beef cows.     

Genetic variation in fatness and fatty acid composition of crossbred cattle

Mature Hereford cows (766) were mated to 97 sires from seven breeds (Jersey, Wagyu, Angus, Hereford, South Devon, Limousin, and Belgian Blue), resulting in 1,215 calves born over 4 yr (1994 to 1997). These cattle comprised Australia's 'Southern Crossbreeding Project." Heifers were slaughtered at an average of 16 mo with hot standard carcass weight of 219 kg and 9 mm fat over the rump. Steers were slaughtered at an average of 23 mo with carcass weight of 319 kg and 13 mm fat over the rump. Meat and fat samples were taken from the carcass on the day after slaughter for subsequent laboratory analysis of i.m. fat content and fatty acid composition. Data were analyzed using uni- and bivariate animal models containing fixed effects of cohort, management group, birth month, and sire breed. March-born calves had fat with a 0.5 degrees C lower melting point, 0.6% higher total monounsaturated fatty acids, and 0.7% higher fatty acid desaturation index than calves born in April. Steers born in 1997 were the only cohort finished on pasture, and they had much more yellow fat than the other cohorts. Four heavy breed crosses (Angus, South Devon, Limousin, and Belgian Blue) averaged 284 kg carcass weight, followed by purebred Hereford (268 kg), Wagyu (244 kg) and Jersey (236 kg). Angus had the greatest fat depth (14.3 mm), ahead of Hereford and Wagyu (11.9 mm), Jersey (10.7 mm), South Devon and Limousin (9.9 mm) and Belgian Blue (8.0 mm). Jersey, Wagyu, and Angus had themost i.m. fat (4.6%), followed by Hereford and South Devon (3.8%), and Limousin and Belgian Blue (3.1%). The highly marbled Jersey and Wagyu had softer fat (6% lower fat melting point) than the other breeds. Angus were more highly marbled, similar to Jersey and Wagyu, but had harder fat similar to the leaner breeds. Heritabilities for all traits were low to moderate (16 to 36%). Genetic correlations between fatty add composition and carcass traits were not significant, indicating little evidence of antagonisms between traits that would prevent genetic progress in both production and quality.     

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.