Effect of L-Glutamine in late gestation sow diets on survivability and growth of piglets Final Report APL Project 2014/463 June 2016 Rivalea Australia Rebecca Athorn and Dave Henman PO Box 78 Corowa NSW 2646 Disclaimer: The opinions, advice and information contained in this publication have not been provided at the request of any person but are offered by Australian Pork Limited (APL) solely for informational purposes. While APL has no reason to believe that the information contained in this publication is inaccurate, APL is unable to guarantee the accuracy of the information and, subject to any terms implied by law which cannot be excluded, accepts no responsibility for loss suffered as a result of any party s reliance on the accuracy or currency of the content of this publication. The information contained in this publication should not be relied upon for any purpose, including as a substitute for professional advice. Nothing within the publication constitutes an express or implied warranty, or representation, with respect to the accuracy or currency of the publication, any future matter or as to the value of or demand for any good.
Acknowledgements This project is supported by funding from Australian Pork Limited and the Department of Agriculture and Water Resources. 2
Executive Summary Reducing pre-weaning mortality in the Australian pig industry would not only have economic benefits for pig producers but also social and animal welfare benefits. Increased sow prolificacy over recent years has led to an increase in pre-weaning mortality not only in Australia but across the world. Countries such as Denmark, where pre-weaning mortalities of around 13% are the norm (due to large litter sizes - 20% if stillbirths are included) (Hales et al., 2015), are now facing pressure from consumer groups to reduce pre-weaning mortality as it is viewed negatively especially in terms of ethics and welfare. In Australia pre-wean mortality levels average around 12% (18% including stillbirths) (Australian Pig Annual 2012-2013), so there is definitely room for improvement. The approach to reducing pre-weaning mortality in pigs is multi-factorial, taking steps in the right direction that reduce any one of the factors involved will be beneficial in helping to reduce overall preweaning mortality. A major factor to consider is the nutrition of the sow during late gestation in order to try and improve piglet birth weight and viability. One such nutritional strategy is the provision of L- Glutamine in sow gestation diets. Previous research into the inclusion of L-Glutamine in sow gestation diets have shown promising results with a study using gilts showing that supplementing gestation diets with 1% L-Glutamine between day 90 and 114 of gestation increased average piglet birth weight and significantly reduced variation in piglet birth weight (Wu et al., 2011). Therefore the aim of this study was to see whether or not the inclusion of L-Glutamine in gestation diets fed from day 80 of lactation until farrowing to multiparous sows under Australian conditions would improve piglet birth weights and decrease within-litter variability in piglet birth weights therefore improving piglet pre-weaning survival and growth. Unfortunately, in this study the inclusion of L-Glutamine in late gestation diets of multiparous sows did not lead to an improvement in piglet birth weights or overall pre-weaning survival or growth, despite higher levels of Immunoglobulin G (proxy for colostrum ingestion and/or quality) measured in blood serum from piglets born to those sows fed the L-Glutamine. It is therefore recommended that L-Glutamine not be included in gestation diets of sows in Australia. Additionally, if benefits were to be seen they would have to quite significant in order to counteract the substantial cost of glutamine. 3
Table of Contents Acknowledgements 2 Executive Summary 3 Background to Research 6 1. Objectives of the Research Project 7 2. Research Methodology 8 2.1 Animals 8 2.2 IgG sample and analysis 9 2.3 Statistical methods 9 3. Results 9 4. Discussion 10 5. Implications & Recommendations 11 6. Literature cited 12 4
List of Tables Table 1. Diet specifications (%) 8 Table 2. Litter characteristics of sows fed either a standard Control diet or a diet supplemented with 1% Glutamine from Day 80 of gestation until farrowing. Values are means ± SEM. 9 5
Background to Research The energy requirement of newborn piglets is very high because of physical activity (locomotion, suckling and attempts to take ownership of the mammary gland) and for thermoregulation (Theil et al. 2014). Recently, a substantial increase in pre-weaning piglet mortality has been observed in association with selection of sows with increased prolificacy (Quesnel et al. 2013). As the number of piglets born per litter increases the energy required by the neonatal piglet increases as littermates compete for colostrum. In addition to this, an increase in litter size ultimately results in a decrease in the average birth weight (as well as increased within-litter variability in birth weight) of the piglet (Foxcroft et al. 2009). Low birth weight piglets also have a decreased capacity to ingest colostrum which puts them at a significant disadvantage to their larger littermates (Amdi et al. 2013). Another problem with low weight piglets is that they have a greater energy requirement per kilogram of birth weight because of their high surface to volume ratio (Noblet and Etienne 1987) and are therefore susceptible to hypothermia which depletes the energy stores they are born with before they even get a chance to reach the udder (Quesnel et al. 2013). Decreasing within-litter variation in birth weight (particularly in sows with large litters) is one strategy that may improve neonatal survival of piglets. One way this may be achieved is through the supplementation of sow gestation diets with L-Glutamine. L-Glutamine is an abundant amino acid in fetal tissue proteins and a major energy substrate that is important for growth and development (Wu et al. 2010). In a study using gilts, Wu et al., (2011) indicated that supplementing gestation diets with 1% glutamine between day 90 and 114 of gestation increased average piglet birth weight and significantly reduced variation in piglet birth weight (25 gilts per treatment). Furthermore, Hewitt and van Barneveld (2012) looked at the inclusion of glutamine (as mono-sodium glutamate) in lactation diets on piglet performance and concluded that it lead to an increase in piglet pre-weaning growth. Therefore, this project aimed to investigate whether or not the inclusion of L-Glutamine in late gestation diets would improve piglet birth weights, decrease within-litter variability in piglet birth weights thereby improving piglet pre-weaning survival and growth. 6
1. Objectives of the Research Project This project set out to identify gestational nutritional strategies that would improve piglet survival and growth. 7
2. Research Methodology 2.1 Animals At day 80 of gestation 460 Large White x Landrace (PrimeGro) multiparous sows (parity 1-8) were allocated to either a Control diet (commercial gestation diet) (n=218) or a diet containing L-Glutamine (n=242) at an inclusion rate of 1%. Diets are presented below in Table 1. Sows were housed in groups of 40 or 80 and fed a 2.4 kg ration daily via Electronic Sow Feeder (ESF). At approximately 110 days of gestation sows were transferred to the farrowing accommodation where they remained on their allocated diets until they farrowed. After farrowing all sows received a standard lactation diet for the duration of lactation. Within 24 hours of birth live piglets were individually weighed and received an ear tag for individual identification. Piglet mortalities and removals were recorded throughout the lactation period. At weaning individual weights of the piglets were again measured. Table 1. Diet specifications (%) Ingredient Control L-Glutamine Wheat 43.7 43.7 Barley 25 25 Millmix 15 15 Hull mixture 4 4 Canola meal 36% 5 5 Meatmeal 59% 2 2 Water 1 1 Natuphos 5000 0.01 0.01 Semi refined fish oil 0.2 0.2 Tallow 1.5 1.5 Limestone 1.2 1.2 Dicalphos Bin Add 0.6 0.6 L-Glutamine 1.0 Lysine micro 0.18 0.18 Threonine micro 0.02 0.02 Sow replace pak micro 0.11 0.11 Repro blend micro 0.025 0.025 Salt bin micro 0.3 0.3 Vitamin blend A micro 0.07 0.07 Vitamin blend B micro 0.05 0.05 Analysis DE, MJ/kg 12.94 12.97 Crude protein (%) 13.49 14.25 Fat 3.49 3.45 Fibre 5.81 5.75 Av Lys/ DE 0.04 0.04 8
2.2 IgG sample and analysis Within 24 hrs of birth a blood sample was obtained from by vena jugular venepuncture from 427 piglets (Control, n=216; Glutamine, n=211) for analysis of Immunoglobulin G (IgG) as a proxy for colostrum intake. The total concentration of immunoglobulin G (IgG) was measured by Pig IgG ELISA Kit (Bethyl, Medist, Montgomery, TX, USA) along with ELISA Starter Accessory Kit (Bethyl, Medist, Montgomery, TX, USA) in blood plasma, after plasma dilution, 1 100000. The assay was performed as per the manufacturer s instructions. Plates were washed by automated 96-well plate washer (Biotek, Elx 50). Finally, absorbance was read at 450 nm using a microplate reader (Biotek Elx808). 2.3 Statistical methods Data were analysed using GLM analysis or a Chi-square test (for piglet survival) (IBM SPSS, v. 21.0; USA). The sow was the experimental unit and data means were separated by least significant differences (P<0.05). Replicate and sow parity were included in the analysis as covariates. 3. Results There was no difference in the total number of piglets born or piglets born alive between the treatments (see Table 2). The average birth weight and variation in birth weight of piglets born alive did not differ between treatments, nor did the variation in weaning weights. There was a trend for piglets from sows fed the L-Glutamine diet to have a lower weaning weight compared to those from sows fed the L-Glutamine diet (P>0.10). Table 2. Litter characteristics of sows fed either a standard Control diet or a diet supplemented with 1% Glutamine from Day 80 of gestation until farrowing. Values are means ± SEM. Control Glutamine P value Total pigs born per litter 13.02 ± 0.21 13.03 ± 0.22 0.975 Total pigs born alive per litter 11.72 ± 0.19 11.74 ± 0.20 0.945 Average birth weight of all piglets born alive (kg) 1.53 ± 0.02 1.51 ± 0.02 0.318 Variation in birth weight among all piglets born alive* (%) 18.97 ± 0.43 19.10 ± 0.48 0.843 Average piglet weaning weight^ (kg) 7.45 ± 0.08 7.25 ± 0.08 0.070 Variation in piglet weaning weights^* (%) 21.28 ± 5.50 22.05 ± 5.27 0.316 ˆage at weaning included in the analysis as a covariate. * CV = (SD/mean) x 100% Piglet survival within the first 24 hours after birth was higher for those piglets from sows fed the L- Glutamine supplemented diet (95 vs. 94%; x 2 = 4.05, P=0.044). However, overall pre-weaning survival was not different between treatments (83.3 vs. 82.9%; x 2 = 0.13, P=0.72), for the L- Glutamine and Control diet fed sows, respectively. The average IgG concentration in piglet serum tended to be higher in the piglets from sows fed L- Glutamine (21.42 ± 0.66) compared to Control sows (19.69 ± 0.65, P=0.061). 9
4. Discussion To the best of the author s knowledge this is the first study in Australia looking at the effect of L- Glutamine inclusion in sow diets fed during late gestation in order to improve piglet birth weights and survival. A study conducted in the USA by Wu et al, (2011) reported an improvement in birth weight as well as a reduction in the variation in birth weights of piglets born alive to gilts fed a diet supplemented with 1% Glutamine during late gestation. Multiparous sows typically have a higher litter number than primiparous sows (gilts) therefore we believed if were to see an improvement in birth weight or a reduction in inter-uterine growth retardation (IUGR) it would be in older sows where uterine space is a limiting factor. However, our results showed that overall there was no difference in the number of piglets born alive, their birth weight or the variation in birth weight between the treatments. Additionally, no benefit was seen of feeding L-Glutamine to a particular parity group. Diets fed in the current study were wheat and barley based compared to the corn and soya bean based diets fed in the study of Wu et al, (2011 ). Hewitt and van Barneveld (2012) suggested that Glutamine levels in Australian sow diets may already be adequate due the availability and inclusion of animal based protein meals and therefore this may be the reason as to why no further improvement was seen in the current study. Additionally, Wu et al, (2011) suggest that Glutamine levels may be restricted due the restricted feeding levels of gestating animals in order to control maternal energy intake, thereby restricting maternal protein intake. At the time of the study sows received 2.4 kg per day and therefore were not restricted to levels that would lead to insufficient protein intakes in the majority of animals. At farrowing all sows were switched to a HE lactation diet and hence L-Glutamine was not included in the sow s diet from this point. However, it is interesting to note that overall average weaning weight was 200g lower for piglets weaned from the L-Glutamine treatment compared to the Control treatment. In a previous study for the Pork CRC, Hewitt and van Barneveld (2012) investigated the inclusion of Glutamine as Glutamic acid or mono-sodium glutamate (MSG) in lactation diets in order to discern its effect on piglet weaning weights and survival. They reported that feeding MSG resulted in an increase in piglet growth rate during the lactation period, however there was no difference in weaning weight between the piglets from sows fed either the control, MSG or Glutamic acid supplemented diets. It is not entirely clear why in the current study piglets from the Glutamine treated sows tended to have lower weaning weights, but one possible explanation is that more piglets were fostered in this treatment compared to the Control treatment and this setback may explain this difference in weaning weight. Immunoglobulin G (IgG) was measured in a subset of piglets within 24 hrs of birth as a proxy for colostrum intake, with the hypothesis being that piglets with higher levels of IgG consumed more colostrum or colostrum of a better quality than those with lower levels. Interestingly, there was a trend for piglets in the L-Glutamine treatment to have higher levels of IgG on average than those in the Control treatment which may have meant that they either had a) more energy (or vigour (not measured)) at birth and more readily reached the udder or b) colostrum was of a better quality in those sows fed L-Glutamine. Unfortunately though, this higher level if IgG did not result in improved survival overall even though survival at 24 hours post-birth was significantly higher for those piglets in the L-Glutamine treatment. 10
5. Implications & Recommendations In this study the inclusion of L-Glutamine in late gestation diets of multiparous sows did not lead to an improvement in piglet birth weights or overall pre-weaning survival or growth. It is therefore recommended that L-Glutamine not be included in gestation diets of sows in Australia. Additionally, if benefits were to be seen they would have to quite significant in order to counteract the substantial cost of glutamine. 11
6. Literature cited Australian Pig Annual 2012-2013. Australian Pork Limited. Amdi, C., Krogh, U., Flummer, C., Oksbjerg, N., Hansen, C.F., and Theil, P.K., (2013). Intrauterine growth restricted piglets defined by their head shape ingest insufficient amounts of colostrum. Journal of Animal Science 91, 5606-5613. Foxcroft, G.R., Dixon, W.T., Dyck, M.K., Novak, S., Harding, J.C., and Almeida, F.C., (2009). Prenatal program of postnatal development in the pig. Society for pig reproduction and fertility supplement 66, 213-231. Hewitt, R. and Van Barneveld, R. (2012). Supplementing lactating sow diets with glutamine to improve milk yield and growth of piglets. Pork CRC final report. Hales, J., Moustsen, M.A., Nielsen, M.B.F. and Hansen, C. F. (2015). Temporary confinement of loosehoused hyperprolific sows reduces piglet mortality. Journal of Animal Science 93, 4079 4088. Noblet, J. and Etienne, M., (1987) Metabolic Utilization of Energy and Maintenance Requirements Lactating Sows, Journal of Animal Science 64, 774-781. Quesnel, H., Gondret, F., Merlot, E., Loisel, F., and Farmer, C., (2013). Sow influence on neonatal survival: a special focus on colostrum. Society of Reproduction and Fertility 69, 117-128. Theil, P.K., Lauridsen, C., and Quesnel, H., (2014). Neonatal piglet survival: impact of sow nutrition around partuition on fetal glycogen deposition and production and composition of colostrum and transient milk. Animal 8, 1021-1030. Wu, G., (2010) Functional amino acids in growth, reproduction, and health. Advances in Nutrition 1, 31-37. Wu, G., Bazer, F.W., Johnson, G.A., Knabe, D.A., Burghardt, R.C., Spencer, T.E., Li, X.L., and Wang, J.J., (2011). Triennial Growth Symposium: Important roles for L-glutamine in swine nutrition and production. Journal of Animal Science 89, 2017-2030. 12