RELATIONSHIP BETWEEN PUBERTY IN HEIFERS AND THE CESSATION OF LUTEAL ACTIVITY AFTER NUTRITIONAL RESTRICTION

The relationship between puberty and the cessation of luteal activity after nutritional restriction was evaluated in 15 Angus X Herefoud heifers. Heifers attained puberty at a body weight of 297 (s.e. 6) kg and a body condition score (BCS) of 5.5 (s.e. 0.1) on a scale of 1 (emaciated) to 9 (obese). After 154 (s.e. 16) days of nutritional restriction, heifers became anoestrus at a weight of 273 (s.e. 8) kg and a BCS of 3.0 (s.e. 0.2). The Spearman's rank correlation coefficient between date of puberty and date of cessation of luteal activity was (r = -0.49; P < 0.06). This indicates that the heifers that attained puberty first were the last to cease luteal activity during nutritional restriction.