Effect of genetic group and feed system on locomotion score, clinical lameness and hoof disorders of pasture-based Holstein–Friesian cows

peer-reviewedThe aim of the present study was to determine the effect of the genetic group of the Holstein–Friesian (HF) and pasture-based feeding system (3 × 2 factorial arrangement) on locomotion score (six gait aspects scored from one to five), clinical lameness and hoof disorders within a seasonal calving milk production system. The three genetic groups compared had an average Economic Breeding Index (EBI) value of 40, 70 and 80: representing the Irish national average genetic merit (LOW-NA), high EBI genetic merit of North American ancestry (HIGH-NA) and high EBI genetic merit of New Zealand ancestry (HIGH-NZ), respectively. Two feed systems were compared: a high grass allowance, low-concentrate system typical of spring-calving herds in Ireland (control) and a high-concentrate system. Data from 126 cows collected across a complete lactation period were analysed using generalised estimating equations and survival analysis. Genetic group of HF had a significant effect on locomotion score, clinical lameness and hoof disorders. Higher EBI cows (HIGH-NA and HIGH-NZ) had lower hazard of poor locomotion score in some gait aspects (e.g. spine curvature) and lower odds of clinical lameness in the first 200 days post-calving (Odds ratios 0.08 and 0.24, respectively, relative to the LOW-NA) and some hoof disorders (e.g. traumatic lesions) compared with LOW-NA cows. The high-concentrate feed system showed a higher incidence and severity of digital dermatitis (P < 0.01). Thus, high EBI cows have better locomotion, fewer cases of clinical lameness and less-severe hoof disorders (i.e. digital dermatitis, white line disease and traumatic lesions) than low EBI cows. These findings have important implications for cow welfare and productivity

Effect of progesterone supplementation in the first week post conception on embryo survival in beef heifers

Progesterone is essential for establishment and maintenance of pregnancy in mammals. The objective of this study was to examine the effect of elevating progesterone during the different physiological stages of early embryo development on embryo survival. Estrus was synchronized in cross-bred beef heifers (n = 197, ∼2-years old) and they were inseminated 12–18 h after estrus onset (=Day 0). Inseminated heifers were randomly assigned to 1 of 3 treatments: (1) Control, n = 69; (2) progesterone supplementation using a Controlled Internal Drug Release Device (CIDR) from Day 3 to 6.5, n = 64; or (3) progesterone supplementation using a CIDR from Day 4.5 to 8, n = 64. Body condition (BCS) and locomotion scores (scale of 1–5) were recorded for all animals. Animals with a locomotion score ≥4 (very lame) were excluded. Embryo survival rate was determined at slaughter on Day 25. Conceptus length and weight were recorded and the corpus luteum (CL) of all pregnant animals was dissected and weighed. Supplementation with exogenous progesterone increased (P < 0.05) peripheral progesterone concentrations, but did not affect embryo survival rate compared with controls. Mean CL weight, conceptus length and conceptus weight were not different between treatments. There was a positive relationship (P < 0.04) between the increase in progesterone concentrations from Days 3 to 6.5 and embryo survival rate in treated heifers and a similar trend existed between the increase from Days 4.5 to 8 (P < 0.06). There was also a positive relationship (P < 0.05) between the progesterone concentration on Day 6.5 and the embryo survival rate in treated heifers. A direct correlation was seen between locomotion score and embryo survival rate, with higher (P < 0.05) early embryo survival rates in heifers with a lower locomotion score. In conclusion, supplementation with progesterone at different stages of early embryo development increased peripheral progesterone concentration and resulted in a positive association between changes in progesterone concentration during the early luteal phase and embryo survival rate. Supplementation with progesterone had no effect on either CL weight or conceptus size in pregnant animals. Lameness had a significant negative effect on early embryo survival.Author has checked copyrightAM