Limiting Amino Acids in Low Crude Protein Broiler Diets
Research was conducted to determine the level of l-Lysine that can be included in corn-soybean meal (C-SBM) diets for broilers before an amino acid other than methionine, lysine, threonine or glycine becomes limiting and to determine the order of limiting amino acids in low crude protein C-SBM diets. All experiments were conducted with Ross 708 broilers (0 to 18 d of age) in brooder batteries. Treatments contained 7 or 8 replicates with 6 birds per replicate. In all experiments, a control C-SBM diet containing no l-Lys.HCl and a positive control diet with supplemental glycine to provide 2.32% total dietary glycine plus serine were fed. All diets were formulated to contain 1.26% total lysine. All diets with added l-Lys.HCl contained supplemental glycine to provide 2.32% total dietary glycine plus serine.

In a series of five studies, the researchers systematically determined the limiting amino acids in a C-SBM based broiler diet. They found that up to 0.25% l-Lys.HCl could be added to C-SBM diets supplemented with methionine, threonine and glycine with no negative effects on average daily gain, average daily feed intake or feed utilization efficiency. They further found that arginine and valine are equally limiting after the bird’s lysine, methionine, threonine and glycine needs are met. (Comment-Bottom line is that reducing crude protein levels in broiler diets requires greater attention to amino acid levels and balance).

Waguespack, A.M. and co-workers. 2009. Effect of incremental levels of L-lysine and determination of the limiting amino acids in low crude protein corn-soybean meal diets for broilers. Poultry Sci. 88(6):1216-1226.

Genetic Improvement of Soybeans
Researchers at the Institute of Crop Science and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences in Hangzhou, China reported on the effect of two new low phytic acid (LPA) mutations on seed quality and nutritional traits. Studies conducted at different locations and different seasons showed that the two mutations did not affect the concentration of crude protein, any of the individual amino acids, crude oil, and individual saturated fatty acids. One mutant (Gm-lpa-TW75-1) had consistently higher sucrose contents (+47.4 to +86.1%) and lower raffinose contents (-74.2 to -84.3%) than those of wild type parent (Taiwan 75). The other mutant (Gm-lpa-ZC-2) had higher total isoflavone contents (3038.8 to 4305.4 microg/g) than its parent (1583.6 to 2644.9 microg/g) in all environments. Tests of homozygous F(3) progenies of the cross Gm-lpa-ZC-2 x Wuxing # 4 (WT variety) showed that LPA lines had a mean content of total isoflavone significantly higher than wild type lines. The research group indicated that this study demonstrated that two LPA mutant genes have no negative effects on seed quality and nutritional traits and the mutant genes may have the potential to improve a few other soybean seed properties. They also postulated that these two mutant genes could be valuable genetic resources for breeding soybean varieties with reduced phytic acid seed levels and may have the potential to improve the nutritional value of soybean meal and lessen phosphorus pollution in large scale animal farming.

Yuan, F.J., and co-workers. 2009. Effects of two low phytic acid mutations on seed quality and nutritional traits in soybean (Glycine max L. Merr). J. Agric. Feed Chem. 57(9): 3632-3638.

Soybean Hulls Use-Dairy
Two experiments were conducted to evaluate the fermentation characteristics of ensiled wet corn distillers grains with solubles (WDG) alone or mixed with soybean hulls (SH) and the ability of the mixture to maintain growth performance in dairy heifers. The first experiment was an ensiling study using laboratory silos. Ensiled blends were 100% WDG, 85% WDG with 15% SH, and 70% WDG with 30% SH on an as-fed basis. Silos were opened for analysis on days 0, 3, 7, and 21. The pH was less in the 100% WDG compared with other treatments (P < 0.01), but all treatments had a pH near 4. Lactic acid concentration was greater in 100% WDG compared with the blends of WDG and SH (P < 0.01). Acetic acid was not found in 100% WDG and increased over time in the 2 blends (P < 0.01). Other differences between blends, such as DM, CP, ammonia N, fiber, and fat, were reflective of the different concentrations of WDG and SH in the blends. In the second experiment, the 70% WDG and 30% SH (as-fed) blend was ensiled in a silo bag and then evaluated as a feed for growing dairy heifer diets. Twenty-four heifers were used in a randomized complete block design and assigned to be fed 1 of 3 diets: 1) control, 2) low inclusion of WDGSH, and 3) a high inclusion of WDGSH. All treatment diets consisted of 50% brome grass hay on a DM basis. The control diet had 50% of the diet (DM basis) as a grain mix, which was composed of corn, soybean meal, and minerals. The low WDGSH diet contained 24.4% of the blend and 25.6% grain mix. The high WDGSH diet contained 48.7% of the blend and 1.3% mineral mix. Average daily gain and most of the body growth measures were similar among treatments. However, dry matter intake decreased linearly (P < 0.01) as the WDGSH blends were fed, resulting in improved G:E (P = 0.02). Results from these experiments indicated that WDG can be effectively ensiled with SH and sustain adequate growth rate when fed to growing dairy heifers.

Anderson, J.L., and co-workers. 2009. Ensiling characteristics of wet distillers grains mixed with soybean hulls and evaluation of the feeding value for growing Holstein heifers. J. Animal Sci. 87(6):2113-2123.