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The use of genomics and accumulation of larger phenotypic databases have helped increase the pace of genetic improvement in the last decade and necessitates nutritionists to re-evaluate the amino acid requirement of the latest, most improved genetics. Despite the fact that sow nutrition research has historically been only about 2% of the swine scientific literature, new commercial facilities with capacity to record weight and feed intake have helped significantly improve the execution of large scale studies.
Gestation
In theory, the greater the litter size the higher the amino acid requirement during gestation. That is well illustrated and supported by nitrogen balance studies. However, several recent randomized large-scale empirical studies under commercial conditions have not been able to confirm the need for increased amounts of amino acids in late gestation. Buis et al. (2016) challenged the factorial approach by feeding gilts and sows throughout gestation with a “Precision feeding” program vs. a simple flat program. In the precision feeding program, diets were changed everyday based on amino acids and energy requirements from NRC (2012) compared to a flat program with a fixed energy and amino acid level. There were no production or reproductive differences between the treatments. Rather than phase feeding by stage of gestation, the current state of knowledge would support segregated feeding by parity category (i.e., gilts, sows). This could create a savings opportunity given a diet formulated for sows would be cheaper than a gilt diet due to its lower amino acid requirement.
A recent study by Thomas et al. (2018) fed 936 females either 11, 13.5, 16.0, or 18.5 g of digestible Lysine per day throughout gestation in a high performing herd with an average litter size of 15.6 total born. Increasing digestible lysine during gestation increased female lean body weight gain and reduced stillborn rate; however, revealed no improvements in piglet birth weight or litter size. This reinforces that the current recommendations, at a weighted average of 12.8 g/d of digestible lysine, seems adequate.
Interestingly, stillborn rate was reduced for sows, but not gilts, by 0.27% for every extra 1 gram / day of digestible lysine when fed throughout gestation (Thomas et al., 2018) or by 0.15% for every extra 1 gram / day when fed starting on day 90 of gestation (Gonçalves et al., 2016). The economics of stillborn rate and lysine levels can vary by region and ingredient price levels. We developed an excel tool to help support this decision process and it is available by contacting our team. On the other hand, a similar large-scale study by Mallmann et al. (2018a) showed an increase of 1 to 2% in stillborn in gilts when feeding levels were increased in late gestation, thus increasing both energy and amino acid intake. This result is similar to what Gonçalves et al. (2016) observed in sows that were fed higher levels of energy in late gestation. As we put these four studies in perspective, it suggests that increasing amino acid levels alone helps with stillborn rate; however, increasing only energy intake or both amino acid and energy were negative for stillborn levels.
Increasing amount of feed in late gestation from 1.8 kg/d (4 lb) to 2.7 kg/d (6 lb) will increase the feed cost by, approximately, $6 to 9 sow per year, depending on feed costs. Recently, it has been documented that an increase in the amount of feed in late gestation will have a minor influence on birth weight (Tables 1 and 2), and this improvement was due to higher energy level rather than amino acids (Gonçalves et al., 2016). This is contrary to the initial hypothesis that amino acids would increase birth weight and one speculative explanation is that part of the increase in piglet birth weight could have been due to increased glycogen reserves of the piglet. This minor improvement in piglet birth weight has been mostly documented in gilts and is, approximately, 1%. From a practical impact, this difference is of negligible relevance when taking into account the negative effects on stillborn rate and lactation feed intake (Gonçalves et al., 2016; Mallmann et al., 2018a).
Table 1. Descriptive summary of bump-feeding experiments for gilts (PIC, 2018).
| Exp.1 | Parity | Start, d of gestation | Litters per trt, n | Total born, n | Control | Bump feeding | Increased by bump feeding | |||
| Mcal ME/d | g SID Lys/d | Mcal ME/d | g SID Lys/d | Female BW gain, kg/kg of extra feed2 | Piglet birth weight, g | |||||
| Shelton et al. 2009 | G | 90 | 21 | 14.3 | 6.8 | 11.9 | 9.8 | 17.1 | 5.7 | 86 |
| Gonçalves et al. 2016 | G | 90 | 371 | 14.2 | 5.9 | 10.7 | 8.9 | 10.7 | 5.6 | 24 |
| Gonçalves et al. 2016 | G | 90 | 371 | 14.2 | 5.9 | 20 | 8.9 | 20 | 9.1 | 28 |
| Soto et al. 2011 | G | 100 | 24 | 12.5 | 7 | 9.8 | 12.9 | 18.2 | NR | 126 |
| Greiner et al. 2016b | G | 100 | 65 | 13.4 | 5.9 | 9 | 8.8 | 14 | 0 | -120 |
| Mallmann et al., 2018b | G | 90 | 55 | 14.6 | 5.9 | 11.7 | 7.2 | 14.3 | 6.8 | 17 |
| Mallmann et al., 2018a | G | 90 | 243 | 14.3 | 5.9 | 10.8 | 7.5 | 13.8 | 7.6 | 26 |
| Mallmann et al., 2018a | G | 90 | 242 | 14.4 | 5.9 | 10.8 | 9.1 | 13.8 | 9.2 | -1 |
| Mallmann et al., 2018a | G | 90 | 246 | 14.4 | 5.9 | 10.8 | 10.7 | 13.8 | 8.2 | -11 |
| Avg3 | --- | --- | --- | 14.2 | 5.9 | 12.8 | 9 | 14.6 | 7.3 | 12.6 |
| SD | --- | --- | --- | 0.7 | 0.5 | 3.2 | 1.7 | 2.8 | 3 | 68 |
| 1Experiments as identified in the references. 2Based on a corn-soy bean meal based diet, is the amount in kg of BW gain for kg of extra feed above the basal level. 3Weighed based on the number of sows in each study. NR = Non-recorded in the study. *Not statistically significant (P>0.05). | ||||||||||
Table 2. Descriptive summary of bump-feeding experiments for sows (PIC, 2018).
| Exp.1 | Parity | Start, d of gestation | Litters per trt, n | Total born, n | Control | Bump feeding | Increased by bump feeding | |||
| Mcal ME/d | g SID Lys/d | Mcal ME/d | g SID Lys/d | Female BW gain, kg/kg of extra feed2 | Piglet birth weight, g | |||||
| Shelton et al. 2009 | S | 90 | 32 | 12.4 | 7.9 | 11.9 | 11.4 | 19.9 | 5.4 | -109 |
| Gonçalves et al. 2016 | S | 90 | 181 | 15.1 | 5.9 | 10.7 | 8.9 | 10.7 | 9 | 47 |
| Gonçalves et al. 2016 | S | 90 | 181 | 15.3 | 5.9 | 20 | 8.9 | 20 | 10.8 | 19 |
| Soto et al. 2011 | S | 100 | 51 | 12.9 | 7.9 | 11.2 | 13.9 | 19.5 | NR | -69 |
| Greiner et al. 2016 | S | 95 | 128 | 14.7 | 5.9 | 9 | 8.8 | 14 | 7.1 | -40 |
| Mallmann et al., 2018b | S | 90 | 221 | 15.4 | 5.9 | 11.7 | 7.2 | 14.3 | 9 | -4 |
| Avg3 | --- | --- | --- | 14.9 | 6.1 | 12.9 | 8.8 | 15.3 | 8.4 | -1.3 |
| SD | 77 | 1.3 | 1 | 3.9 | 2.4 | 3.9 | 2.1 | 58 | ||
| 1Experiments as identified in the references. 2Based on a corn-soy bean meal based diet, is the amount in kg of BW gain for kg of extra feed above the basal level. 3Weighed based on the number of sows in each study. NR = Non-recorded in the study. *Not statistically significant (P>0.05). | ||||||||||
Lactation
The focus of lactation in feed efficient females continues to be to maximize lactation intake by full feeding sows from farrowing until weaning (Pinilla et al., 2018).
Lysine: Increasing digestible lysine from 42 to 63 g/d in gilts during lactation increased litter weight gain, improved lactation feed conversion, and reduced backfat loss (Bruder et al., 2018). Additionally, to the author’s knowledge, for the first time the offspring from a lysine dose-response study in lactation was followed from birth to carcass (Gourley et al., 2018) and, perhaps not surprisingly, there was no carryover effects from lysine levels on offspring lifetime performance. Graham et al. (2018) evaluated the effects of 43 to 71 g/d of digestible lysine during lactation and observed an improvement in daily litter weight gain up to 57 g/d. However, they found no evidences for differences in any other performance parameters. Interestingly, these two studies failed to show that subsequent performance, such as wean-to-estrus interval and subsequent litter total born, was negatively impacted at the lowest digestible lysine levels. This could add to the body of evidence that improved genetic lines are more robust and resilient than in the past few decades.
Valine: There is a wide range of recommendations for digestible valine to lysine ratio around the globe. However, we have not been able to document benefits above 64% dig. Valine:Lysine or 36 grams / day of digestible Valine (Graham et al., 2018; Touchette et al., 2018)
Threonine: The digestible Threonine to Lysine requirement was recently documented at 65% for maximum litter growth and 68% for maximum subsequent reproduction (Greiner et al., 2017a).
Tryptophan: Greiner et al. (2017b) evaluated a digestible Tryptophan to Lysine ratio from 14 to 20% with no improvements in performance above 17.6%, which is lower than NRC (2012) at 18.9%.
Conclusion
This series of recent amino acid research indicates that current recommendations are adequate for today’s highly prolific sows. During gestation, managing body condition to avoid excess condition seems to be a key to minimize stillborn rate and maximize lactation feed intake. The addition of piglet birth weight in the genetic selection index and observed positive impact from that addition appears to help reduce our need for nutrition interventions for improving birth weight, for example bump-feeding. From the lactation standpoint, full feeding modern highly efficient genetic populations from farrowing to weaning while providing an adequate amount of lysine and other amino acids will maximize litter weight gain. The selection for lean gain and feed efficiency on top of reproductive parameters in maternal lines seem to be paying off by having a resilient female, with high protein turnover capacity, and without greatly increased nutritional requirements despite increased litter size.
