Journal Articles
Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915
Browse
2 results
Search Results
Item Live Weight and Bone Growth from Birth to 23 Months of Age in Holstein–Friesian, Jersey and Crossbred Heifers(MDPI (Basel, Switzerland), 2022-06-01) Gibson MJ; Adams BR; Back PJ; Hickson RE; Dittmer KE; Rogers CWSelection pressure for greater milk solid production, calving ease and early puberty attainment has resulted in the alteration of the growth trajectory of New Zealand dairy heifers. Although previous data have looked at stature growth in terms of height and girth, changes in the growth trajectory as a result of seasonal growth has not been examined. In addition, the relative contributions of the appendicular skeleton and thorax in relation to height have not been considered in previous studies. Therefore, the aim of this study was to examine how the proportional contributions of stature change with increases in live weight in Holstein–Friesian, Jersey and Holstein–Friesian–Jersey crossbred heifers from birth to 23 months of age (just prior to calving). Comparisons of height, length, girth and distal and proximal forelimb length (stature) revealed that at the same live weight, measures of girth, length and height did not differ between breeds (p < 0.05). As live weight increases, the relative contribution of the distal limb to increasing height decreases, which is consistent with the cessation of physeal growth occurring earlier in the bones of the distal limb than in the proximal limb. By understanding the timing of proximal and distal growth in dairy heifers, the effect of seasonal growth on longitudinal bone growth can be identified.Item Genetic Parameters for Maternal Performance Traits in Commercially Farmed New Zealand Beef Cattle(MDPI (Basel, Switzerland), 2021-08-26) Weik F; Hickson RE; Morris ST; Garrick DJ; Archer JA; Michael E DMaternal performance is a major driver of profitability in cow-calf beef cattle enterprises. The aim of this research was to evaluate the inheritance of maternal performance traits and examine the intercorrelation among reproduction, live weight, hip height, body condition and maternal contribution to calf weaning weight in 15-month-old heifers, 2-year-old cows and mature cows in New Zealand beef herds. Data were collected on a total of 14,241 cows and their progeny on five commercial New Zealand hill country farms. Heritabilities were low for reproductive traits in heifers and mature cows (0-0.06) but were greater in 2-year-old cows (0.12-0.21). Body condition scores were lowly (0.15-0.26) and live weights (0.42-0.48) and hip heights (0.47-0.65) highly heritable in heifers, 2-year-old cows and mature cows. Results indicate that 2-year-old cows with higher genetic potential for rebreeding ability may have greater genetic merit for live weight, hip height and body condition as heifers (rg = 0.19-0.54) but are unlikely to be larger cows at maturity (rg = -0.27--0.10). The maternal genetic effect on weaning weight had a heritability of 0.20 and was negatively genetically correlated with body condition score in lactating cows (rg = -0.55--0.40) but positively genetically correlated with rebreeding performance (rg = 0.48).