Effect of Calving Difficulties and Calf Mortality on Functional Longevity in Polish Holstein-Friesian Cows

Abstract

Longevity is one of the functional traits that considerably affect dairy herd profitability. A Weibull proportional hazards model was used to evaluate the impact of difficult calvings and calf stillbirths on cow functional longevity, defined as length of productive life corrected for milk production. The data for analysis comprised calving ease and calf mortality scores of 2,163,426 calvings, 34.4% of which came from primiparous cows. The percentage of male calves was 53.4%. Calving ease was scored as “without assistance” (34.44%), “with assistance” (62.03%), “difficult—hard pull” (3.39%), and “very difficult, including caesarean section” (0.14%). Calf mortality scores were “live born” (94.21%) and “stillborn or died within 24 h” (5.79%). The Weibull proportional hazards model included classes of calving ease or calf mortality scores × parity (1, ≥2) × sex of calf as time-dependent fixed effect. The model also included time-dependent fixed effects of year × season, parity × stage of lactation, annual change in herd size, fat yield and protein yield, time-independent fixed effect of age at first calving, and time dependent random herd × year × season. In first-parity cows, very difficult birth of a bull or heifer increased the relative risk of culling, respectively, 2.18 or 1.26 times as compared with calving without assistance. In later parities, the relative risk of culling related to very difficult calving was 2.0 times (for male calves) and 1.33 times (for female calves) higher than the relative risk of culling associated with calving without assistance. Calf mortality showed a negative impact on longevity in both heifers and cows. First-parity stillbirth increased the relative risk of culling depending on sex of calf by 18% in females and by 15% in males; in later parities the increase of the relative risk of culling was lower (by 7% for females, 9% for males). Difficult calvings and their consequences, especially in primiparous cows, may negatively influence dairy herd profitability by reducing the length of cows’ productive life.

Estimation of Dairy Cow Survival in the First Three Lactations for Different Culling Reasons Using the Kaplan–Meier Method

“…An increased percentage of milk fat was related to the higher culling risk for most culling categories, especially in the second and third lactations. A similar advantageous effect of protein content and a more neutral influence of fat content on the culling rate was found by Sasaki et al [ 110 ], Chirinos et al [ 111 ], and Morek-Kopeć et al [ 109 ].…”

“…In the present study, the HR value for the percentage of milk protein was below unity for almost all culling categories, which suggested a decreased culling risk. A similar effect of increased milk protein content on culling rate was observed by Morek-Kopeć et al [ 109 ], indicating that a lower protein content associated with the lactation stage and difficult calving may contribute to the culling of a cow. An increased percentage of milk fat was related to the higher culling risk for most culling categories, especially in the second and third lactations.…”

Identification of cow-level risk factors and associations of selected blood macro-minerals at parturition with dystocia and stillbirth in Holstein dairy cows

“…The percentage of male and female calves in this study was 50.5% and 49.5%, respectively, and male calves were more likely to be stillborn, which is consistent with the results of Maltecca et al 59 that male calves have a higher risk of stillbirth than female calves. According to a recent study, the stillbirth rate for male calves (7.7%) was more than twice as high as that of female calves (3.7%) 60 . Mellado et al 61 found that calves with a birth weight of < 35 kg had the highest probability of stillbirth, which is in line with our findings.…”

Causes and Effects of Stillbirths on Days Open and Cow Herd Survival in Holstein Friesian Cows

“…In a recent research, Morek-Kopec et al (2021) [19] reported for Polish Holstein Friesian cows that stillbirth rate from male calves at calving was 7.7% and for female calves 3.7%.…”