The Effect Of Protein Intake During Gestation And Lactation On Mammary Development Milk Production And Subsequent Reproduction Of Primiparous Sows

Author : Tai Yuan Chen
Publisher :
ISBN 13 :
Total Pages : 258 pages
Book Rating : 4.:/5 (13 download)

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Download or read book Dietary Energy Manipulations and Reproductive Performance in Primiparous Sows written by Tai Yuan Chen and published by . This book was released on 2012 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: In primiparous sows, feed intake is generally insufficient to meet lactation demands during lactation. Inadequate nutrient supply increases mobilisation of body reserves during lactation and, as a consequence, affect subsequent reproduction. Excessive loss of body reserves during lactation is not only associated with delayed post-weaning oestrus and the size of the subsequent litter, but also increases culling rate and reduces sow longevity and the productivity of the breeding herd. The aim of the thesis was to develop a clear understanding of the impact of a negative energy balance during lactation affects reproductive performance of modern primiparous sows in Australia, and evaluate feeding strategies involving energy manipulations during crucial periods for improving subsequent litter size. In the first study, the associations of sow body weight changes during lactation and the body weight at weaning with subsequent reproductive performance were studied. By minimising body weight loss and maintain adequate body reserves at weaning through the supply of sufficient energy when rearing equal to or less than ten piglets during lactation, the post-weaning reproduction of modern primiparous sows may not be affected. In the second study, the carry-over effects of energy intake during the early antral phase and subsequent follicular phase on follicle recruitment and ovulation rate were assessed using a gilt model. Follicle size at the end of the luteal phase was greater for gilts that were previously fed at a high feed level. During the follicular phase, high feeding increased follicle size at Day 5 and plasma oestradiol concentration. Nevertheless, a low feed level during the luteal phase reduced ovulation rate and the number of embryo, and this was not counteracted by feed level during the follicular phase. Plasma progesterone concentration after ovulation was lower for gilts that were restricted-fed throughout the whole period than for other treatments. These results indicate that undernutrition during early antral follicular development may have a residual effect on follicle recruitment and quality. In the third study, the effects of substituting 1 kg of a standard lactation diet with 1 kg of a sugar-rich or fat-rich diet during late lactation on blood glucose and insulin changes were investigated. The results suggest that a sugar-enriched diet during the last week of lactation elevates circulating glucose and insulin concentrations, and may potentially improve post-weaning fertility in primiparous sows. Therefore, the fourth study investigated the effects of pre-weaning energy substitutions plus post-weaning altrenogest treatment as positive control on follicular development, endocrine characteristics and subsequent litter size in primiparous sows. The weaning-to-ovulation interval tended to be reduced in the sugar-rich treatment, although body weight loss during the treatment period, post-weaning follicle development, plasma oestradiol and pre-weaning leptin did not differ among treatments, except body weight loss was lower and leptin was higher in the altrenogest treatment. Post-ovulatory progesterone concentration in the sugar treatment was higher. Sows in the sugar-rich and altrenogest treatments had a greater proportion of litters with larger litter sizes. The outcome indicates that increasing circulating insulin and glucose concentrations during late lactation or a week of metabolic recovery positively improves subsequent litter size in primiparous sows. Industry will be able to achieve and improvement of reproductive performance by maximising energy intake (using an insulin-stimulating diet) during late lactation, or by post-weaning altrenogest administration for a week for energy restoration. Otherwise, adverse impacts of a negative energy balance during lactation will be carried over into the mating period, and will depress subsequent reproductive performance.