Effects of ad libitum mineral consumption in Iberian red deer hinds and calves

Abstract

Minerals are essential nutrients for ungulates because they cannot be synthesised. Lactation is the most mineral-demanding stage for hinds, whereas for calves both the pre- and post-weaning growth periods are important for bone formation, among other processes. Because both physiological effort and hot Mediterranean climate may increase mineral needs even in a situation under an ad libitum high plane of nutrition, we examined the effects of free-choice, single-mineral consumption in red deer hinds and their calves during lactation, and in the calves, from 18 to 56 weeks after lactation. Group M had permanent access to minerals, the control group had no access, whereas the LM and PLM groups of calves had access to minerals only during lactation or after lactation, respectively. Hinds with or without mineral supplements during lactation did not show differences in weight or body condition, neither did female calves of any group during or after lactation. However, after controlling the effect of year, LM male calves achieved greater weight gains during the post-lactation experiment, whereas the PLM and M groups showed negative results in weight at the end of the post-lactation experiment and age of antler growth initiation, respectively. The LM group also achieved higher scores in all the studied first antler variables (length, weight, burr perimeter, and perimeter in the middle of the antler) after controlling the effects of weight and year. The results thus suggest that, under ad libitum access to high-quality food, mineral supplementation is only positive during lactation. However, it cannot be ruled out that minerals may be beneficial in other stages in free-ranging deer.