Health disorders and their association with production and functional tratits in Holstein Fresian cows

Logistic regression models were used for studying the relationships between milk yield, body condition score (BCS), somatic cell score and some disorders of periparturient cows (mammary edema and retained placenta) with the occur- rence of ovarian cysts, clinical mastitis and lameness. Data from milk recording (milk yield and somatic cell content) col- lected at nearly monthly intervals (time period: 35 ± 3 d) were merged with BCS recorded on the same dates of milk recording on periparturient heifers, lactating and dry cows, and with health disorders data (retained placenta, severe mammary edema, ovarian cysts and clinical mastitis and lameness) collected during regular herd activities over nearly 3.5 years. Data were from one commercial herd consisting of over 200 lactating dairy cows and exhibiting an average 305-d milk yield of nearly 10,000 kg. A total of 5,315 records from 728 lactations and 429 cows were used in the analy- ses. The time period incidence rate was 11.9%, 6.6% and 4.6% for ovarian cysts, lameness and mastitis, respectively, and the lactational incidence rate was 44.1%, 33.4% and 28.1% for ovarian cysts, lameness and mastitis, respectively. Occurrence of both ovarian cysts and mastitis was more common in the early lactation than afterwards, whereas lame- ness tended to occurr erratically during lactation. The risk of occurrence of mastitis and lameness was lower in primi- parous when compared to multiparous cows. The increase of milk yield increased the risk of occurrence of ovarian cysts (odds ratio: 1.32, P < 0.01) and of mastitis (odds ratio: 1.12, P < 0.10), whereas no significant relationship was found between milk yield and lameness. An increase of somatic cell score was found to be a risk factor for mastitis (odds ratio: 1.36, P<0.01) and for the occurrence of lameness (odds ratio: 1.06, P<0.05). The occurrence of relative risk of disor- ders was not related to BCS at calving, and monthly variation of BCS was related to the onset of mastitis only. Retained placenta did not appear to present a risk factor for the occurrence of diseases of concern, whereas the presence of severe mammary edema at calving increased the risk of mastitis occurrence by nearly 50%. Regular recording of herd health data seems advisable for a better understanding of the relationships between production and functional traits and the occurrence of health disorders.