Association of interservice interval with conception rate in Japanese Black cattle

Economic loss due to treatment of bovine respiratory disease in Japanese Black calves arriving at a backgrounding operation in Miyazaki

The present study assessed the economic loss due to treatment of bovine respiratory disease (BRD) in Japanese Black calves that were introduced to a backgrounding operation from the age of 3 to 4 months until the age of 10 months. The data collected from a backgrounding operation in Miyazaki, Japan included the records of 2,690 animals entering the farm from 2013 to 2018. The treatment duration was defined as the number of days from the beginning to end of treatment. The cost of treatment was defined as the total cost of treatment during the treatment duration. The average incidence of BRD was 54.6%, and the relative frequency of calves that had BRD once, twice, and three or more times until they left the farm was 64.4%, 26.8%, and 8.8%, respectively (total recorded diagnoses of BRD: 2,494). Among the 2,494 recorded diagnoses, the average and median duration of treatment of BRD was 5.9 days and 3.0 days, respectively. The average and median cost of treatment was 7,767 and 5,600 Japanese yen, respectively. A prolonged duration of treatment and high cost of treatment were associated with BRD relapse, steers, and early stage of production (P<0.05). At the studied farm, the total cost of treatment during the 6-year study period was 19,658,988 yen, and the annual cost was approximately 3 million yen. In summary, the present study showed that BRD had a large economic impact in this backgrounding operation.

Impact of dystocia and cow/calf characteristics on mortality from 0 to 120 days of age in Japanese Black calves in commercial cow-calf operations

Calf mortality severely affects productivity in the beef industry. The present study was conducted to assess the calf mortality risk (CMR) in Japanese Black calves and investigate potential associations between calf/cow information and the CMR. Records for calves born between April 2006 and March 2010 were extracted from an existing database, which included production data on commercial cow-calf operations in Miyazaki, Japan. The study group comprised 40,462 calves born to 15,600 cows on 908 farms. Because calves on the studied farms were weaned at approximately 4 months of age, the calf records were collected from birth to 120 days. The CMR was calculated as the number of dead calves divided by the number of surviving calves. Mixed-effect multivariable logistic regression modeling was used to determine potential associations between the CMR and the factors hypothesized to influence that risk. CMR analyses were performed separately for the following production stages: days 0-30, days 31-60, days 61-90 and days 91-120 after birth. Of the 40,462 calves, 1465 died during days 0-120 after birth, and the CMR was 3.6 %. Of the 1465 dead calves, 35.9 % died within 10 days after birth. During the 0-30-day period, the CMR was associated with dam parity, calving status, gestation length, sex, birth season and twin births (P < 0.05), but not with the number of inseminations to conception. Low parity, dystocia, gestation lengths < 280 days and > 301 days, male calves, calves born in autumn and winter and twin births yielded higher CMRs. Low dam parity also yielded higher CMRs during the 31-60-day, 61-90-day and 91-120-day periods (P < 0.05), but no other factors were associated with the CMR during these periods. Thus, various cow and calf factors were shown to be associated with CMRs in Japanese Black calves, and calves with these factors should be considered high-risk calves.

Random Regression Analysis of Calving Interval of Japanese Black Cows

Simple Summary

Genetic parameters for the calving interval of Japanese Black cows were estimated by using a random regression model and a repeatability model. Legendre polynomials based on age at previous calving, ranging from 18 to 120 months, were used as sub-models for random regression analysis. The estimated heritability for the calving interval was low and was similar between the models. The estimated genetic correlation between ages was always higher than >0.8. Spearman’s rank correlation of the estimated breeding values between the two models was ≥0.97 for cows with their own records and ≥0.94 for sires of these cows. Therefore, this study supports the validity of fitting a repeatability model to the records of the calving interval of Japanese Black cows for breeding value evaluation. Our results could contribute to determining strategies for selection and management of Japanese Black cattle.

Abstract

We estimated genetic parameters for the calving interval of Japanese Black cows using a random regression model and a repeatability model. We analyzed 92,019 calving interval records of 36,178 cows. Pedigree data covered 390,263 individuals. Age of cow at previous calving for each record ranged from 18 to 120 months. We used up to the second-order Legendre polynomials based on age at previous calving as sub-models for random regression analysis, and assumed a constant error variance across ages. Estimated heritability was 0.12 to 0.20 with the random regression model and 0.17 with the repeatability model. With the random regression model, the estimated genetic correlation between ages was ≥0.87, and those between 24 and 36 months, 24 and 84 months, and 36 and 84 months were 0.99, 0.95, and 0.97, respectively. Spearman’s rank correlation between breeding values of 36,178 cows with their own records estimated by the random regression model with those estimated using the repeatability model was ≥0.97, and the rank correlation was ≥0.94 for 314 sires of these cows. These results support the validity of fitting a repeatability model to the records of the calving interval of Japanese Black cows for evaluation of breeding values.

Association of postpartum diseases occurring within 60 days after calving with productivity and reproductive performance in dairy cows in Fukuoka: A cow-level, retrospective cohort study

Peripartum disorders in dairy cows negatively influence their productivity and reproductive performance. However, only a few reports have clearly indicated the influence of such disorders on the productivity and reproductive performance at a local-area or cow-level in Japan. This study aimed to elucidate the influence of diseases occurring within 60 days after calving on subsequent productivity and reproductive performance. Accordingly, a wide-area database on dairy production was used for epidemiological analysis; subsequently, multivariable analysis was performed to investigate the association of such diseases with productivity or reproductive performance in 6,545 cows from 178 farms in Fukuoka. We used 305-day energy-corrected milk (305 ECM) as an index of productivity and conception and culling as indices of reproductive performance. With regard to causality, mixed-effects model was used for analyzing the association between disease and productivity, and Cox proportional hazard model was used for analyzing the association between disease and reproductive performance. Compared to the disease absence group, the disease presence group demonstrated significantly lower 305 ECM [-154 kg; 95% confidence interval (CI), -229 to -79] and risk of pregnancy [hazard ratio (HR), 0.85; 95% CI, 0.80-0.91] and higher risk of culling (HR, 1.36; 95% CI, 1.17-1.59). These results indicate that, in Fukuoka, dairy cows affected by diseases within 60 days after calving exhibit lower productivity and reproductive performance. Therefore, proper dairy cow management during the peripartum period to prevent diseases during early lactation may maintain or improve productivity.

Effect of oestrous resynchronization on the reproductive efficiency of zebu cows

The aim of this study was to develop a resynchronization strategy before the return of oestrus in cows diagnosed as not pregnant after fixed-time artificial insemination (TAI). A total of 839 cows, approximately 45 days post-partum, were synchronized using TAI. On day 0, intravaginal progesterone-releasing devices were inserted and 2 mg of oestradiol benzoate was administered. Eight days later (D8), the progesterone-releasing devices were removed and oestradiol cypionate (0.5 mg, eCG [300 IU]) and prostaglandin (7.5 mg) were administered. All cows were inseminated between 48 and 56 hr after device removal (D10). Thirty days after TAI, cows that were not diagnosed as pregnant by ultrasound were immediately resynchronized and again inseminated at a fixed time. The hormonal protocol used in the first and second rounds of TAI was the same. The pregnancy rate after the first TAI was 52%, and after the second TAI, it was 49%. The increase in the total pregnancy rate (synchronization + second oestrous synchronization) compared to a single synchronization was 23.5%. In conclusion, resynchronization of oestrus and ovulation in zebu cows that had previously undergone TAI protocols is effective in increasing the reproductive efficiency.