By Mark Knauer, North Carolina State University
Feed costs are the largest expense in swine production. Hence management strategies that reduce sow feed cost can provide a positive return on investment for pig farmers. Reducing gilt size at breeding is one management strategy that can cut sow feed costs.
Improperly managed, gilt weight at breeding impacts both cost and income. When compared to lighter weight females, gilts mated at heavier weights consume more feed during the gilt development period (Klindt et al., 1999) and have greater feed maintenance requirements throughout their lifetime (Newton and Mahan, 1993). Yet gilt weight at breeding also influences income. Mating gilts at heavier weights decreases piglet survival (Newton and Mahan, 1993). These results are supported by Bryan (2014) who reported increased sow weight, more so than parity, was a key driver of reduced piglet survival.
What gilt breeding weight maximizes producer profit? Perhaps it depends on your farm’s Parity 1 lactation feed intake and lactation diet composition. Clowes et al. (2003) suggests increased body weight at breeding and farrowing reduces lactation effects on modern gilts. Hence, increasing first parity lactation amino acid intake by enhancing lactation feed intake, amino acid composition or both may allow you to mate gilts at lighter weights.
What data needs to be collected to determine optimal gilt weight at breeding? Specific treatments can be utilized to alter gilt weight as observational studies can be misleading. Gilt weight at breeding can be manipulated by initiation of boar exposure or restrictive feeding. Yet some confounding still exists with either strategy. Example data to obtain includes gilt feed intake, breeding weight, gestation feed consumption, body condition, lactation feed intake and reproductive performance.
Any farms interested in collaborating on a project of this nature feel free to contact me.
Bryan, M. Associations among body condition, reproductive performance and body lesions in group housed sows. M. S. Thesis. North Carolina State University, Raleigh.
Clowes, E. J., F. X. Aherne, G. R. Foxcroft, and V. E. Baracos. 2003. Selective protein loss in lactating sows is associated with reduced litter growth and ovarian function. J. Anim. Sci. 81:753-764.
Klindt, J., Yen, J. T., Christenson, R. K. 1999. Effect of prepubertal feeding regimen on reproductive development of gilts. J. Anim. Sci. 77:1968-1976.
Newton, E. A., and D. C. Mahan. 1993. Effect of initial breeding weight and management system using a high-producing sow genotype on resulting reproductive performance over three parities. J. Anim. Sci. 71:1177-1186.