Long-Term Effects of Winter Supplement on Growth and Development of Hereford Range Females

Abstract

For 10 consecutive winters beginning at the age of 8 months, 120 Hereford females were fed Low, Moderate, High and Very High levels of supplement to determine long-term effects of level of supplement on body growth and development. In addition, one-half of the Very High level cows were switched to the Moderate level after three winters. Body weight, width at the hips, height at the withers, distance from chest floor to ground and length of body were determined in the spring and fall of each year. Body weights for the Very High level cows (735 kg) were still increasing at 6 years of age and probably would have increased further if supplement had not been reduced to this group to prevent excessive obesity. Body weights for the Low, Moderate and High level cows were lower and tended to plateau at 6.5 years of age. Cow weights and most body measurement tended to parallel the levels of winter supplement throughout the study. Patterns observed in the fall and spring measurements indicated that all measurements were influenced varying degrees by external body fat. When cows fed the Very High level of supplement for the first three winters were switched to the Moderate level, their weight and body measurements decreased until they closely resembled those of the Moderate level cows, suggesting that most of the additional weight and increase in body measurements attained by the High and Very High level cows close to or after maturity was due to fat deposition.