263 Review of Current Nutrition Knowledge and Practices for Gilt Development

Abstract

\n Nutrition for replacement gilts aims to support the development of prepubertal gilts towards their physiological maturity in terms of body weight, body tissue composition, structural soundness, and reproductive development. A key concept of gilt nutrition for lifetime productivity is to maintain a positive prepubertal growth rate and reach a target body weight of 115 to 140 kg at puberty. The application of this concept commonly presents a challenge with fast-growing and highly efficient contemporary gilt lines, particularly considering the proportion of gilts exceeding the target body weight at puberty and the negative impacts of overweight gilts on lactational performance, structural soundness, and longevity. Thus, nutritional decisions regarding dietary levels of energy, amino acids, and minerals in the pre- and peripubertal stage can be conflicting. Typically, gilts are fed ad libitum with moderate levels of energy and amino acids because restrictions below the requirements can have a negative effect on puberty onset. In addition, a high plane of nutrition is offered after the pubertal estrus to set ovulation rate for breeding at the next estrus. Moreover, gilts are fed levels of dietary calcium, phosphorus, and trace minerals above the requirements to improve bone mineral density in preparation for fetal development and lactation mobilization. Although these nutritional practices improve gilt performance, they also typically increase weight gain. Thus, there is a need to review nutritional strategies to manage body weight of replacement gilts while attaining optimum reproductive success and lifetime productivity.