Do feed level, diet, and parity during weaning-to-estrus affect sow reproductive performance?

To improve reproductive performance, sows are usually fed at a high feed level during the weaning-to-estrus interval (WEI). However, in the modern genetic lines the WEI has been reduced to a point in which the impact of feed level on performance may have been reduced. Therefore, the aim of the present study was to assess the effect of two feeding levels (moderate feeding level (MFL): 2.7 kg/day and high feeding level (HFL): 4.3 kg/day) and two diet types (gestation: 13.67 MJ/kg of metabolizable energy (ME) and 0.62% of standard ileal digestible lysine (SID Lys) and lactation: 14.34 MJ ME/kg and 1.20% of SID Lys) offered during the WEI on reproductive performance. For that purpose, from 1320 initial sows and due to the variability in feed intake among them, a total of 254 primiparous and 806 multiparous Landrace × Large White crossbred sows were included in the study. Follicular size and change in BW were measured in subsamples of 180 and 227 females, respectively. The experimental design consisted in a 2×2×2 factorial arrangement (feeding level, diet type and parity). Data were analyzed considering the sow as the experimental unit.

As a result, the feed intake of MFL and HFL groups averaged 2.5 ± 0.02 and 3.8 ± 0.02 kg/day, respectively. There was an interaction between feeding level and parity for daily feed intake. Within HFL, multiparous sows consumed more than primiparous sows, but no difference was observed within MFL. Sows lost proportionally less weight when fed HFL than MFL diets. The WEI was not affected by feeding level, diet type or its interaction, but it was longer in primiparous than in multiparous sows. Moreover, there was no effect of feeding level, diet type, parity or their interactions on anestrus and farrowing rates. As expected, multiparous sows showed greater follicular size, and greater numbers of total born and born alive piglets than primiparous sows.

In conclusion, a high feeding level in primiparous and multiparous sows fed with 4.3 kg/day of a gestation (58.78 MJ ME and 26.66 g SID Lys) or a lactation diet (61.66 MJ ME and 51.60 g SID Lys) does not improve follicular size or reproductive performance.

Gianluppi R, Lucca M, Mellagi A, Bernardi M, Orlando U, Ulguim R, Bortolozzo F. Effects of different amounts and type of diet during weaning-to-estrus interval on reproductive performance of primiparous and multiparous sows. Animal. 2020; 1-10. https://doi.org/10.1017/S175173112000049X