Late gestation is a critical stage in the breeding cycle of the sow. Continual improvements in the genetic performance and our improved understanding of the changing nutritional requirements in late gestation now highlight that the traditional approach of bump feeding is no long considered best practice. Genetic advances have developed benefits (increased litter size) together with challenges like increased litter weight variation and reduced birth weights. Getting the nutrition right in late gestation can have substantial benefits for both the sow and her litter and the overall profitability of your pig enterprise. This article will examine some of the nutrition aspect of late gestation nutrition to optimise sow and progeny performance.
Why bump feeding isn’t a worthy compromise
Bump feeding is a term used to describe the typical increase (e.g. 20-30%) in daily feed allowance of the gestation diet in the last 3-4 weeks of gestation. This approach will satisfy the increased energy requirement of the sow and her litter but does not meet the protein requirement nor the changing requirement in specific amino acids. Increasing the bump feeding level further to meet the protein requirement isn’t advisable either as the risk of over weight sows will likely result in poor milk output during lactation. For those producers who are serious about making the best use of their modern genetics the practical options include either using a specific pre-lactation diet or a pre-lactation top dress in late gestation.
Amino acids requirements in late gestation
Research outcomes are now showing us that the ideal amino acid pattern relative to lysine shifts in late gestation. Unfortunately the full profile is not yet available. A review of the current literature shows that the lysine requirement increases by roughly 55% from mid to late gestation and also highlights that low density gestation diets can be used effectively in mid gestation where the lysine requirements is low (mean 10.66g/day SID Lysine, range 6.9 to 16.3g/day SID Lysine), with higher requirements in young parity sows who are still undergoing their own body growth. Deficiencies in lysine in late gestation can negatively influence insulin and prolactin and subsequently disrupt the smooth transition into lactogenesis (Zhang et al., 2011). Research is also showing that there is a disproportionate increase in the requirements of other amino acids including threonine, isoleucine and tryptophan (Fig 1.)
Figure 1. Percentage increase in SID amino acids from mid to late gestation based on a review of the current literature.
Glutamine is another amino acids which is rarely mentioned in sow nutrition but it is known to be important in late gestation to ameliorate fetal growth retardation and also to reduce preweaning mortality (Wu et al 2015). The requirement for glutamine is in fact estimated to be higher in late gestation than in lactation (Wu 2014). Glutamine is also known to be an important amino acid for milk production. Piglets which experience intrauterine growth restriction have been shown to have restricted plasma concentrations of both glutamine and arginine in late gestation relative to normal body weight piglets (Lin et al, 2012). There is no established dietary recommendation for glutamine in late gestation and lactation diets, however there are a number of studies showing positive responses from the dietary supplement of L-glutamine and/or MSG. Personal experience on commercial farms is also delivering improvements in piglets born alive and weaning weights when diets are formulated to a total glutamine level of 3.75-4.0%.
Arginine is a known vasodilator and consequently can improve the nutrient and oxygen supply from the sow to the foetal mass. In addition to this arginine is also postulated to be involved in gene expression in the umbilical vein and thus regulate angiogensis, vascular development and function of both the placenta and umbilical vein (Lui et al 2012). Supplementary arginine (1%) whilst expensive has been shown to improve birth weight, nutrient utilisation, fetal survival, immunity (circulating IgM & IgG) and vaccine response in sows (Che et al., 2013). Basal arginine levels in diets vary depending on composition. Personal experience with supplemental L-arginine in commercial diets has not yet delivered economic results. This may be due to the relatively high level of arginine in the raw materials used in Australian sow diets (legumes, animal proteins and oil seeds) or the lower reproductive performance of Australian sows due to closed genetics.
Fatty acid profile manipulation
There is also reasonable evidence to show that manipulation of the fatty acid profile in late gestation diets can improve the quality of colostrum and the vitality of new born pigs. However, the research is not yet complete and not always easy to interpret. Conjugated linoleic acid and fish oil (rich in omega 3 fatty acids) have been used successfully in late gestation and lactation diets at a rate of 0.5% (Bontempo et al., 2004, Tanghe et al., 2015). Research also suggests though that commercial nutritionists need to formulate diets to an omega 6:omega 3 ratio (<5) as well as considering the absolute level of omega 3 in the diet and the conversion efficiency of C18:3(n-3) to longer chain n-3.
Mineral and vitamin requirements
More than 50% of the total mineral retention (macro & micro) occurs during the last two weeks of gestation (Mahan, 2006). Higher producing sows have a greater requirement for minerals than lower producing sows and the critical periods for minerals are in late gestation and lactation. Mineral depletion is known to occur over a 3 parity period (Mahan & Peters, 1994) so to ensure sow longevity is not compromised the strategic use of high quality and high bio-avialable (organic) minerals are useful in late gestation and lactation. Minerals and vitamins which provide needed antioxidant protection (organic selenium, vit E, vit C) to the sow and her progeny are also recommended in late gestation. You may consider a specific pre-farrow vitamin and mineral premix.
A smooth farrowing transition
Another advantage of having a separate pre-lactation diet or top dress is that it allows economical application of functional feed ingredients to optimise the farrowing transition. Careful consideration of fibre level and fibre source are encouraged to find a positive balance between digesta transit rate (avoiding constipation) and extracting the advantage of slow release energy derived from hind gut fermentation (in restrict fed mature sows) to improve birth weight. The use of probiotics, organic acids and phytogenics is also recommended in this brief period to enhance gut health in the sow and subsequently in her progeny.
Finding the economic balance
The recommendations above may sounds costly, however by carefully reviewing both your early gestation and pre lactation diets, it is possible to keep the feed cost per sow per gestation close to neutral. By having a separate pre-lactation diet you can refine your early gestation diet to better meet the needs of the sow and the minimal needs of her developing litter. The money saved over the first 13 weeks of gestation can then be reinvested into the pre-lactation diet to better meet the needs of the sow throughout gestation and to produce a better quality and more consistent litter.
The evolution of genetics in modern sows requires nutritionists to evolve their diets and feeding programs accordingly. The constraints placed on the genetic potential of sows in commercial farms (environment, housing, climate, labour) also need to be considered when customising your nutrition approach. Significant gaps remain in the research of hyper-prolific sows and these knowledge shortfalls will need to be filled quickly if nutrition is to keep up with genetic advances. However, there is good reason to apply the research outcomes already achieved to make better use of the genetics we have today. Nutritionist need to consider not only the role of nutrition on metabolism but also on hormone regulation and subsequent reproduction. Considering conditionally essential nutrients like glutamine and vitamin C at critical times will also be important.