Impact of increased energy and amino acids in sow lactation diets on piglet performance in large litters Aimee-Louise Craig*1, 2 and Dr. Elizabeth Magowan1, 2 *Corresponding author: aimee-louise.leslie@afbini.gov.uk 1Agri-food and Bioscience Institute, Hillsborough, Northern Ireland. 2Queens University, Belfast, Northern Ireland. Note: Do not change background, font or font colours.

Introduction Weaning weight is a critical factor in determining pig lifetime performance (Mahan and Lepine, 1991; Le Dividich et al., 2003) During the suckling period the pig is highly efficient at converting nutrients to lean gain (Pluske and Dong, 1998) An extra 1kg in weaning weight could reduce the days to slaughter by 10 days (Cole and Close, 2001) Therefore, increased gain during this period will improve whole farm efficiency. The difference in weight is not simply maintained, but magnifies as the pig grows, as heavier pigs grow faster than light pigs. The suckling period, and likewise the lactating sow, is of utmost importance in the economics of pig farming.

Introduction There are two main challenges to piglet weaning weight: Larger litter sizes negative correlation between litter size and birth weight (Quiniou, 2002) positive correlation between birth weight and weaning weight (Dunshea et al., 2003) Sow milk yield Limiting to piglet growth Suckling piglets have the potential to gain 576g/day if fed ad libitum (Hodge, 1974), but when suckling the sow piglet gains average 240g/day. There is concern that larger litter sizes achieved through recent genetic selection have had a negative impact on individual piglet weaning weight.

Introduction Total litter weaning weight can be improved through increasing: Energy (Walsh et al., 2012; Xue et al., 2012; Smits et al., 2013) Lysine (Heo et al., 2008; Yang et al., 2009; Xue et al., 2012) Valine (Riechert et al., 1996; Moser et al., 2000; Paulicks et al., 2003) in the sow lactation diet Valine has the greatest oxidation rate in the mammary gland of any amino acid (Trottier et al., 1996) Valine becomes the second limiting amino acid when sows do not mobilise body tissues (Kim et al., 2001) From previous studies, we have found:

Introduction These studies are limited for commercial production due to the small litter sizes tested. Very few papers (2008-2014) report nutritional requirements for sows based on litter sizes over 11.5 (Craig et al., 2015). In 2013, the EU average for piglets born alive per litter was 13, with six countries attaining more than 13 pigs born alive per litter, the highest being Denmark at 15.4 (BPEX, 2014). How do we feed these sows to achieve good weaning performance?

Back to Basics! Milk yield = 4.2 x piglet growth (mean of several studies as estimated by van der Peet-schwering et al., in the Lactating Sow, 1998) Maintenance for a 250kg sow is 28.9 MJ ME (Noblet et al., 1998) Milk energy requirement is 5.4 MJ ME/kg (BSAS Nutrient Requirement Standard, 2003) Tables for lysine requirement as described in BSAS Nutrient Requirement Standard, 2003 (based on maintenance plus amount required for milk production) Starting with these assumptions, we formulated diets according to how we expected the sows to perform.

Back to Basics! Therefore: 13 pigs growing from 1.5kg at birth to 9kg at 28d Will have an ADG of 3.48kg/day Require an average of 14.63kg of milk/day Total energy required by sow: 112.37 MJDE/d Lysine requirements: 91.7g total lysine /day Intake requirements: 8kg/day (average over 28d lactation) 14MJ DE 1.15% lysine From these assumptions we estimated the nutrient requirements of sows rearing various litter sizes. Note that the sow needs to achieve an average of 8kg of feed intake a day over a 28 day lactation period. Total energy includes maintenance and assumes that there is no backfat loss.

Back to Basics! 14 pigs growing from 1.5kg at birth to 9kg at 28 d Will have an ADG of 3.75kg/day Require an average of 15.75kg of milk/day Total energy required by sow: 118.69 MJ DE/day Lysine requirements: 99.2g total lysine /day Intake requirements: 8kg/day (average over 28d lactation) 14.8 MJ DE 1.24 %lysine

Aim of Current Study Provide the sow with a balance of energy and lysine, as recommended in the BSAS Nutrient Requirement Standards for Pigs (2003), to enable her to wean: litters of 13 pigs average of 9kg individual weight at weaning (28d) Test the effect of a higher Lysine:Valine ratio in lactation diets. Test the effectiveness of phase-feeding during lactation From these calculations we designed diets to:

Materials and Methods Animals: PIC F1 or PB Landrace Sows representing parity 2-6 (n=109) were selected, based on weight and condition score. PIC 337 was the terminal sire used. Measurements: Individual piglet weight at 0,5,7,10,14, 21 and 28 days Sow milk composition at 0,5,7,10,14, 21 and 28 days Sow blood urea nitrogen at 21 days Daily sow feed intake Sow BCS, P2 and weight. Piglets had no creep and where individually tattooed and then tagged. Sows had access to a wet and dry feeder and were offered 3kg/day of their respective lactation diet until the day of farrowing, after which feed allowance was increased by 0.5kg/day until intake reached 10kg/day. The target average feed intake over the 28 day lactation was 8kg/day. Feed allowance was recorded individually on a daily basis and the daily allowance was offered across two meals. Feed disappearance was recorded as feed intake.

Treatments 2 x 2+1 factorial design: Control (13.5 MJ DE/kg, 0.88% Lysine, 0.66% Valine) Flat (14.4 MJ DE/kg, 1% lysine) or Phased (Flat diet offered until day 14 of lactation followed by a second diet containing 15MJ DE/kg, 1.1% lysine until 28 days) High (Lys:Val 1:1.1) or Normal (Lys:Val 1:0.68) lysine:valine ratio Dietary treatments began at day 108 of gestation and were offered in a 2x2+1 design as follows:

Materials and Methods : Diets Formulated and Actual Analysis Flat Phased Control Norm Valine High Valine Formulated Composition DE (MJ/kg) 13.5 14.4 15 CP (%) 17.0 19.8 19.9 20 Lysine (%) 1.0 1.25 1.4 Valine (%) 0.82 0.95 1.50 1.10 1.68 Lysine:Valine 1:0.82 1:0.76 1:1.2 1:0.79 Actual composition 13.6 14.1 14.9 15.1  15.9 17.4 15.6 16.2 0.88 0.92 1 1.11 0.96 0.67 0.62 1.2 0.77 1.03 1:0.67 1:0.69 1:1.07 Within this study, actual analysis of the dietary treatments differed from the formulated analysis . The lysine content of the diets did not increase as expected between the flat and phased dietary regime treatments. Energy did increase as expected; therefore the phased treatments represent an increase in energy only as opposed to an increase in energy and lysine. This has then meant that the treatments represented different energy to lysine ratios. The ratio of lysine to valine  across treatments was as expected despite the actual valine content being lower than expected.

Results Average lactation length - 28.2 days Mean sow parity - 3.6 Average number of pigs after cross-fostering - 13.4 Average number of pigs weaned - 12.8 Daily feed intake was significantly different (P=0.003) between the control group (7.1kg) and the treatment groups (7.7kg) and was used as a covariate for production analysis.   Treatment effects on sow and litter performance and diet effect on milk composition were assessed by analyzing the data as a 2x2+1 using Genstat (16th Edition) using the analysis of variance (ANOVA) model. There was no significant difference between treatments on BCS change or P2.

Interactive effects of diet on litter and pig performance Flat Phased Interactions Ctrl Norm Valine High Valine SEM (P Value) Litter weight(kg) Day 0 18.98 20.99 19.23 19.59 19.51 0.672 0.208 Day 28 102.1 111 109.3 108 111.7 2.490 0.272 Litter ADG (kg) Day 0-28 2.96 3.17 3.19 3.16 3.27 0.077 0.547 Individual Piglet Weight (kg) 8.22 8.32 8.59 8.65 8.70 0.081 0.178 Individual Piglet ADG (kg) 0.239 0.243 0.252 0.255 0.257 0.003 0.169 There was no significant effect of individual treatment on weight or ADG at weaning on either a litter basis or individual piglet basis. No Interactions between treatments

Control vs Treatment effects of diet on litter performance Flat Phased Ctrl Norm Valine High Valine SEM Effects (P-Value) Litter weight (kg) Day 0 18.98 20.99 19.23 19.59 19.51 0.672 0.285 Day 14 58.09 65.01 64.82 60.00 63.74 1.682 0.007 Day 28 102.1 111 109.3 108 111.7 2.490 0.006 Litter ADG (kg) Day 0-14 2.79 3.06 3.20 2.89 3.12 0.101 0.015 Day 14-28 3.39 3.54 3.42 3.69 0.126 0.161 Day 0-28 2.96 3.17 3.19 3.16 3.27 0.077 0.008 However, treatment groups had significantly improved (P<0.01) litter weights and average daily gain compared to the control group. This led to an improvement of 8kg of litter weight at weaning compared to control which is an increase of 7.8% Treatments improved Weight at Weaning by 7.8%

Control vs Treatment effects of diet on pig performance Flat Phased Ctrl Norm Valine High Valine High Valine SEM Effects (P-Value) Individual Piglet Weight (kg) Day 14 4.70 4.90 4.83 4.91 0.044 0.005 Day 21 6.54 6.61 6.86 6.84 6.88 0.063 <.001 Day 28 8.22 8.32 8.59 8.65 8.70 0.081 Piglet ADG (kg) Day 0 - 14 0.218 0.216 0.231 0.228 0.232 0.003 Day 14-28 0.255 0.261 0.266 0.279 0.275 0.004 Day 0 - 28 0.239 0.243 0.252 0.257 Average piglet birth weight was 1.48, but was significantly different (P<0.001) between treatments and was therefore used as a covariate, as was lactation length, number of pigs weaned and sow feed intake. The treatments became significantly different from the control at day 14. The treatments improved piglet ADG and therefore weaning weight was improved by 345g compared to control. Treatments improved weight at weaning by 4.2%

Flat vs. Phased feeding regime effects on litter and pig performance Ctrl Norm Valine High SEM Effects (P Value) Litter weight (kg) Day 28 102.10 111.00 109.30 108.00 111.70 2.490 0.879 Litter Gain (kg) Day 0-28 2.96 3.17 3.19 3.16 3.27 0.077 0.691 Individual Piglet Weight (kg) Day 14 4.7 4.9 4.83 4.91 0.044 0.12 Day 21 6.54 6.64 6.86 6.84 6.88 0.063 0.045 8.22 8.32 8.59 8.65 8.7 0.081 0.007 Individual Piglet ADG (kg) Day 14-28 0.255 0.261 0.266 0.279 0.275 0.004 <.001 0.239 0.243 0.252 0.257 0.003 0.005 Phased feeding had no effect on a litter basis. However, on an individual piglet basis, phased feeding started to improve piglet weight by day 21. By weaning piglet weight had improved by 220g on the phased regime compared to the flat regime. Phased feeding increased weight at weaning by 2.6%

High vs. Normal Lys:Val effect on litter performance Flat Phased Ctrl Norm Valine High Valine Norm Valine High Valine SEM Effects (P Value) Litter weight (kg) Day 0 18.98 20.99 19.23 19.59 19.51 0.672 0.164 Day 14 58.09 65.01 64.82 60 63.74 1.682 0.298 Day 28 102.10 111.00 109.30 108.00 111.70 2.490 0.699 Litter Gain(kg) Day 0-14 2.79 3.06 3.20 2.89 3.12 0.101 0.069 Day 14-28 3.39 3.54 3.42 3.69 0.126 0.628 Day 0-28 2.96 3.17 3.19 3.16 3.27 0.077 0.412 There was no consistent effect between high and low levels of valine at a litter level. However note the trend at day 0-14 ADG as this becomes significant at individual piglet level. No significant effect at litter level

High vs. Normal Lys:Val effect on pig performance Flat Phased Ctrl Norm Valine High Valine Norm Valine SEM Effects (P Value) Individual Piglet Weight (kg) Day 10 3.91 4.04 3.93 4.01 0.075 0.004 Day 14 4.7 4.9 4.83 4.91 0.044 <.001 Day 28 8.22 8.32 8.59 8.65 8.7 0.081 0.049 Piglet ADG (kg) Day 0-14 0.218 0.216 0.231 0.228 0.232 0.003 0.002 Day 14-28 0.255 0.261 0.266 0.279 0.275 0.937 Day 0-28 0.239 0.243 0.252 0.257 0.053 High Lys:Val levels improved piglet weight and ADG from day 10. Piglets from sows fed high Lys:Val feeds were 160g heavier at weaning. 1:1.1 Lys:Valine improved weight at weaning by 1.8%

Milk Yield Milk yield as estimated from piglet growth. Note the peak at day 7, dip at day 10 and ultimate peak at day 14. This could not be explained by feed intake, as feed intake did not plateau until day 14. Phase feeding reduced the decline of milk yield.

Effect of Lysine:Valine on Milk Fat P<0.001 P=0.002 The diets containing high Lys:Val ratio increased the fat content in sow’s milk on day 21 (P<0.001) and 28 (P=0.002) of lactation. However, previous studies have found no effect of Valine level on milk fat. However, it is established that valine is utilised in the mammary gland for purposes other than milk protein synthesis therefore at high levels of inclusion it may increase fat synthesis

Results Milk Composition: Blood Urea Nitrogen. The control group had increased urea nitrogen in milk on day 7 (P=0.03) and 10 (P=0.009) compared to the treatment groups. There was no overall effect of treatment on the protein, casein or lactose content of milk. Blood Urea Nitrogen. No significant difference between treatments. Control group indicates a poor nitrogen balance.

Discussion This study demonstrates that increasing energy and lysine levels above 13.6 MJ DE and 0.88% lysine (Control) in the lactation diet enabled sows to: raise a larger litter (12.8) wean piglets at an acceptable weaning weight (>8.5kg) without compromising body condition and tissue breakdown. Perhaps valine is more readily utilised by younger piglets.

Discussion Treatment sows produced an extra 8kg (7.8%) of litter weight at weaning compared to control sows: This could reduce slaughter age by 5 days/pig May have economic advantages If a finisher pig eats 2.5kg/d 5 days x 2.5kg = 12.5kg 13 pigs x 12.5kg = 162.5kg Cost = £32.5/litter (£200/tn) OR >£7,000 per 100 sows per year...! 0.5kg a piglet. According to Close and Cole

Discussion Phase feeding improved performance by 220g/piglet or 2.6% (P=0.007) compared to flat rate feeding. This could equate to an increase of 2.34kg in litter weight for a litter of 13. Possibility for more gain if phase feeding started earlier in lactation Artificially-reared piglets begin to outstrip their sow-reared counterparts at around day 8-10 of lactation in terms of voluntary food intake (Harrell et al., 1993); however, despite this, the authors were reluctant to introduce diets with such high oil and protein contents too early in lactation due to risk of diarrhoea in the piglets. Therefore, if the second stage diet had been introduced earlier in lactation the potential for growth may have been increased. Indeed, this is an area that warrants further study. nd Cole

Discussion Increased Lys:Val greatly improved piglet growth between day 7 and 14. Effect reduced after day 14, but was still evident at weaning (P=0.049) High Lys:Val (1:1.1) increased pig weight at weaning by 160g (1.8%) compared to normal Lys:Val (1:0.68) Total Valine consumed: 47.7 - 92.4 g/day

What can a sow do? Average Top 25% Top 5% Litter Weaning Weight 108kg Number Weaned 12.8 13.3 13.7 ADFI 7.6 7.8 8.3 BCS Loss -0.4 -0.5 -0.6 P2 Loss -3.6 -4.2 -4.7

Conclusion This study demonstrates that sows are able, if given the correct nutrition, to achieve weaning outputs of 110kg per litter. In practice, this equates to 13 pigs weaned at 8.5kg which is acceptable for good lifetime performance.

Conclusion Consumption of 108MJ DE and 77g of lysine (Flat: Normal Valine) per day is effective at achieving this performance Increasing this intake has potential to further improve performance: Phase feeding Increased lys:val

Acknowledgements Dr. Elizabeth Magowan Dr. Wallace Henry DARD Pig Regen Staff at the Pig Research Unit, AFBI

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