Agri-Plastics focuses on a wide array of sturdy farm accessories designed to enhance efficiency and guarantee consistent performance for your operation. 888-231-3575 • INFO@AGRI-PLASTICS.NET • AGRI-PLASTICS.NET DEALERSHIP OPPORTUNITIES AVAILABLE! Swiss breeds. (Adapted from Duplessis et al., 2014; Table 6). Heifer weight Body weight varies based on breed, age and environment. At 15 months of age, heifers’ body weight ranged from 297 kg for Jerseys, 334 kg for Ayrshires, 379 kg for Brown Swiss cows and 425 kg for Holsteins (Duplessis et al., 2014). The large variances between animals show the need for producers to record all their heifers’ weights and heights and not just a subset population. Average daily gain will impact when a heifer is ready to be bred, and any sickness or period of poor growth will influence age at first breeding. Cows exhibiting slow or poor growth early in life will be delayed in days to first breeding and age at first calving. Monitoring heifer growth will indicate the success of your heifer management program and offer a method by which you can make informed decisions on when to breed heifers according to animal measurements. Based on body weights and heights collected in this study, the age at first breeding showed Holsteins bred at 13.6 months, Ayrshires at 15.5 months, Jerseys at 12.6 months and Brown Swiss at 14.5 months (Duplessis et al., 2014). With the exception of Ayrshire heifers, most heifers reached the optimal weight for breeding before 14 months of age. Timing of weight and height It is interesting to note the researchers observed the time and frequency of weight and height directly influenced the ability to predict 24 months for age of first breeding or a cow’s mature weight and height. For instance, taking five measurements of body weights and heights at weaning was less reliable in predicting weights at 15 months of age than weights taken closer to 15 months of age. Taking body weights of heifers throughout the growth period at regular intervals was more reliable in predicting weight and tracking growth. Although monthly body weight and height records offer more data on the growth of individual heifers, there was little gain in the ability to predict weight at 15 months or 24 months to justify the increase in time and labour to obtain the weights. According to Duplessis et al., 2014, weights should be taken every three months with a minimum of eight measurements from birth to first 51 Promotional Supplement Focus On Dairy | June/July 2024 FOCUS ON DAIRY
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