The impact of essential fatty acid ratios and unsaturated to saturated fat ratio on growth performance of grow-finish pigs and estrus detection of gilts.

ABSTRACT

The objective of this study was to investigate the effects of dietary unsaturated and saturated fat ratio (US) and the ratio of linoleic and linolenic acid (LAALA) on the growth performance of grow-finish pigs and estrus detection of gilts. A total of 240 pigs with initial body weight (BW) 54.4 ± 5.5 kg were randomly assigned to a high (>1.8; HUS) or low (<1.0; LUS) US in combination with a high (201), moderate (121), or low (41) LAALA in a 3 × 2 factorial arrangement. Dietary ratios were achieved using blends of choice white grease, beef tallow, corn oil, flaxseed oil, or palm kernel oil. Diets were fed across three phases and balanced for energy and LA. Pigs were housed across 60 pens with either four gilts or four barrows per pen. On day 49, 1 gilt per pen was moved to individual housing at approximately 154 d of age for evaluation of reproductive characteristics. Data were analyzed as repeated measures using PROC MIXED (SAS 9.4; SAS Inst., Cary, NC) with pen as the experimental unit and US, LAALA, sex, and their interactions as fixed effects. Initial BW was fit as a covariate. Within each phase, there were no differences in BW, daily gain (ADG), feed intake (ADFI), or feed efficiency (GF) for US, LAALA, or their interaction when averaged across sex (P ≥0.128). Gilt feed efficiency was improved during the second phase compared to barrows; however, feed efficiency was not different between barrows and gilts during the first and third phases; resulting in a similar feed efficiency between sexes for the overall period (P = 0.523). Compared to HUS, gilts receiving LUS had higher ADFI overall (P = 0.018), which translated into improved GF for HUS gilts (P = 0.011). Overall, gilts receiving the 201 diet tended to have improved GF compared to 121 (P = 0.086). ADG was improved in pigs fed diets formulated with unsaturated fat sources to a 201 LAALA, regardless of sex. Detection of first estrus by 235 d of age in gilts was not impacted by US or LAALA (P ≥ 0.356). In conclusion, feeding differing dietary US and LAALA ratios impacts growth of growing pigs, particularly improving feed efficiency of gilts fed diets with unsaturated fat sources or a 201 LAALA. Further investigation into the physiological mechanisms differentially affecting gilt growth when fed varying dietary LAALA is warranted to understand the impact on reproductive outcomes.