Catch-up growth of yearling wapiti stags (Cervus elaphus)

Abstract

Ten yearling wapiti stags were used to investigate effects of winter nutrition on subsequent growth on summer pasture. One group of five (LOW) was wintered on medium-quality hay, and the other group of five (HIGH) was wintered on hay and alfalfa–barley pellets (16% crude protein). By the time they grazed spring pasture in mid-April, HIGH wapiti had larger frame dimensions and were 20 kg heavier than those wintered on hay alone, despite their lower pre-winter weights. However, subsequent catch-up growth rapidly narrowed these differences, and both groups attained similar weights and frame measurements by late July. Liveweight gains on summer pasture were 0.30 and 0.15 kg d−1 for LOW and HIGH wapiti, respectively. Although LOW wapiti tended to have higher gut fill (3.3 vs. 2.5 kg dry matter), the difference (corrected for assumed dry-matter content) was insufficient to explain compensatory weight gain. Digestibilities and mean retention times did not differ consistently between the treatment groups but were reciprocally related to one another. Forage intakes rose as pastures flushed but declined sharply in July with overgrazing and resumption of supplemental feeding. LOW wapiti consumed more pasture dry matter than HIGH wapiti in May and June. Efficiencies of forage utilization were unrelated to nutritional history. Using data pooled for the two treatment groups from April to June gave estimates of 878 kJ W−0.75 for maintenance and 33.4 kJ g−1 for liveweight gain. The main factor contributing to compensatory gain on summer pasture was higher forage intakes, particularly in relation to metabolic weight. Key words: Game farming, elk, compensatory growth, forage intake, passage rate, energy requirements