Effects of gestation, lactation, and maternal calcium intake on mechanical strength of equine bone.

This research article investigates how late pregnancy, breastfeeding, and maternal calcium intake influences the strength of horse bones. The study found that bone strength increases in the latter stage of pregnancy in mares that consume the recommended amount of calcium, decreases during early breastfeeding, and then returns to normal afterwards. However, mares on a calcium-deficient diet did not show the same increase in bone strength during pregnancy and their recovery post-breastfeeding was slower.

Objective and Methods of the Research

• The research primarily aims to develop a better understanding of bone health in horses during the last stages of pregnancy, breastfeeding, and the recovery period post-breastfeeding.
• The researchers used horses as their animal model for the study.
• The breaking strength of the metacarpal bone (a bone in the leg of horses), was measured using transmission ultrasonics. These measurements were made during the last 12 weeks of pregnancy and for 40 weeks after childbirth.

Findings of the Research

• It was found that in mares fed amounts of calcium recommended by the National Research Council, bone strength increased during the last 6-10 weeks of pregnancy, reaching maximum at childbirth.
• However, in mares fed 20% less calcium, bone strength remained relatively constant in the last 12 weeks of pregnancy.
• Interestingly, after childbirth, bone strength decreased in all mares during the first 12 weeks of lactation.
• Progressively, bone strength began to recover after approximately 12 weeks of breastfeeding but the rate of recovery was slower compared to the rate of decline.
• Mares fed with recommended calcium amounts fully regained their bone strength at 24 weeks post-childbirth. In contrast, mares deficient in calcium had not fully recovered even 20 weeks after stopping milk production (40 weeks post-childbirth).
• The bones of foals (young horses) born to mares fed a calcium-deficient diet were found to be thinner and mechanically weaker at birth. These differences in bone size and strength persisted during the first 40 weeks of life.

It is thus clear from the findings of the research that the recommended calcium intake plays a crucial role in maintaining and improving bone strength during late pregnancy, lactation, and the post-lactational recovery period in mares.