Protein and non-protein methionine requirements for first parity gestating and lactating sows - Ontario Pork - Completed Research
Sunday, May 26, 2024

Completed Research

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Completed Research

Protein and non-protein methionine requirements for first parity gestating and lactating sows

Protein and non-protein methionine requirements for first parity gestating and lactating sows

Project 18-02 - Lee-Anne Huber, University of Guelph

The NRC (2012) based estimated methionine requirements for gestating and lactating sows from very few studies, with a focus on the retention of methionine in maternal, fetal, and milk proteins. These estimates do not take into account the metabolism of the modern sow (many studies are over 50 years old) or the ‘non-protein’ roles of amino acids, which can use up a significant proportion of the amino acid. Methionine is one such essential amino acid that has over 50 non-protein roles in the body.


  1. Determine the dietary methionine required to maximize whole-body protein retention (sow and products of conception or milk)
  2. Determine the dietary methionine required to optimize methionine use for non-protein roles.
  3. Determine effect of dietary methionine supply on maternal and fetal piglet hoof health.

Two animal studies were completed with 70 and 75 gestating and lactating gilts, respectively. Animals were assigned to diets with increasing methionine supply. Nitrogen balances were completed at various points in gestation and lactation to assess protein retention in the gilt + products of conceptus (gestation) or the gilt + milk (lactation). Blood samples were collected routinely to measure the concentration of non-protein compounds that depend on methionine supply. The dietary methionine level that optimized each outcome was assessed statistically.

To maximize nitrogen (protein) retention in gestation, standardized ileal digestible (SID) methionine should be supplied at 0.17, 0.19, 0.16, and 0.23 % between d 38-41, 53-56, 87-90, and 109-112 of gestation, respectively. Therefore, the current feeding recommendations by the NRC (2012) underestimate methionine requirements of gestating sows. In early lactation, the methionine feeding level required to maximize milk production is possibly below 0.18% SID methionine. In peak lactation, milk production is maximized around the current feeding recommendations of 0.26% SID methionine. Therefore, precision feeding programs can be generated for both gestation and lactation diets to more closely match (daily) estimated methionine requirements and reduce nitrogen losses to the environment. Optimizing the concentrations of products of methionine used for non-protein roles in the body is less clear, but it appears that greater methionine feeding levels are required versus to maximize protein retention. Maternal and fetal piglet hoof health were not assessed, since we found these measurements to be too variable. Instead, a more comprehensive assessment of piglet tissues for accumulation of methionine-dependent non-protein compounds was completed. It seems that as milk protein output increases, the concentration of creatine in piglet plasma decreases, indicating competition between protein and non-protein roles of methionine in the lactating sow.

Therefore, feeding recommendations for methionine for gestating and lactating sows should be updated to maximize protein retention. Further work is required to determine the optimal methionine feeding level for non-protein fates.

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