Nitrogen Effects on Triticale Grain Yield, Amino Acid Composition, and Feed Nutritional Quality for Swine

Nitrogen fertilizer recommendations for triticale (X Triticosecale Wittmack) and soft red winter (SRW) wheat (Triticum aestivum L.) in the southeastern USA are similar in spite of different end uses. Grain yield, protein, and amino acid composition of four triticale cultivars were evaluated over five N levels ranging from 30 to 150 lb/acre in four Georgia environments. Nitrogen was topdressed as ammonium nitrate at peak tillering. Relative economic value of triticale for feed was calculated assuming total replacement of corn (Zea mays L.) plus variable amounts of soybean [Glycine max (L.) Merr.] meal (SBM) in a standard swine diet formulated to 100% of National Research Council (NRC) lysine requirement at representative prices for corn and SBM. Significant grain yield responses to N occurred in three of the four environments. Grain yield was maximized with 90 or 120 lb N/acre depending on environment and cultivar. Yield component responses to N were increased tiller density, decreased seeds per head, and decreased seed weight. Quantity of all amino acids increased linearly with N indicating potential for enhancing nutritional value by increasing N to raise contents of limiting essential amino acids. The superior lysine content of triticale relative to corn resulted in a relative cash price for triticale, which averaged 6% higher than corn value (range 3% to 10%). Despite N-induced increases in lysine content and relative nutrional value of triticale for feed, marginal return per acre was maximized at N levels associated with maximum grain yield. Cultivars varied for all traits except tiller density. Maximum economic return per acre was obtained with improved cultivars Florico and Florida 201, which had higher yield potential and test weight, but lower lysine content, than cultivars Beagle 82 and Morrison. Based on our study using 1997 prices, current N recommendations for small grains of 60 to 120lb N/acre depending on previous crop, are appropriate for triticale. At these N levels, cultivar selection is more important for increasing returns than additional inputs of N. Research QuestionAlthough end use and quality parameters of triticale and soft red winter wheat differ, N recommendations for the two crops are the same in the southeastern USA. High rates of N cause undesirable increases in grain protein content and decreases in milling and baking quality of soft red winter wheat, however N-induced increases in content of limiting essential amino acids could increase the nutritional value of triticale as a feed grain for poultry and swine. This study was conducted to determine triticale cultivar response to N fertilization for grain yield, amino acid composition, and feeding value for swine. Literature SummarySeveral studies with cereal grains have shown that amino acid contents in grain increase as a linear function of N fertilization. Contents of some nonessential amino acids increase faster than contents of some essential amino acids in response to N, and it is generally concluded that protein quality decreases as N input increases. However, with triticale-based diets formulated to meet minimum lysine requirement, N-induced increases in lysine content of triticale grain associated with higher N input could increase the grain's nutritional quality and feed value. Study DescriptionField trials were conducted in 1987 and 1988 at two sites, Tifton and Plains, GA. Soils: Tifton sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudult) and Plains Greeneville sandy clay loam (clayey, kaolinitic, thermic Rhodic Paleudult). Experimental design: Split plot arrangement, randomized complete block, three replications. Main plots (triticale cultivars): Beagle 82, Florico, Florida 201, and Morrison; subplots (N fertilizer rates): 30, 60, 90, 120, and 150 lb/acre. Traits evaluated: Tiller density, kernels per spike, kernel weight, grain yield, test weight, amino acid composition, and protein content. Applied QuestionsWhat type of cultivars should be selected to produce triticale feed grain in the Coastal Plain region of southeastern USA? Improved cultivars, Florico and Florida 201, with higher yield potential and test weight, but lower lysine content, produced higher returns per acre than older cultivars, Beagle 82 and Morrison. Although the lysine content and relative value of Beagle 82 and Morrison were significantly higher, the superior yield potential of Florico and Florida 201 more than offset their lower lysine contents. Should triticale grown for use in swine diets be fertilized with higher rates of N to increase grain nutritional and economic value? No. Despite N-induced increases in lysine content and relative nutritional value of triticale grain for feed, marginal returns per acre were maximized at N levels associated with maximum grain yields. At these N levels, cultivar selection appears to be more important than additional inputs of N to maximize economic returns from triticale. Based on current prices of corn and soybean meal, current Georgia N recommendations for small grains of 60 to 120 lb N/acre depending on previous crop, are appropriate for triticale grown for use in swine diets. Table 1Mean grain yield, test weight, lysine content, relative feed value, and gross return of four triticale cultivars and five N rates over 2 yr at Tifton and Plains, GA. GrainTestLysineRelativeMarginalVariablesyieldweightcontent†value‡return§lb/acrelb/bu%$/cwt$/acreCultivar Florico411652.90.4065.25191 Florida 201387051.20.3995.24178 Beagle 82359548.10.4385.32166 Morrison246346.30.5045.46109 LSD (0.05) 365 3.10.0320.07 19N rates, lb/acre 30286149.80.4015.24142 60348649.90.4135.27166 90372849.70.4315.31172 120383949.50.4585.36171 150364249.30.4815.41154 LSD (0.05) 536ns0.0280.06 29†Drymatter basis. ‡Relative value of triticale assuming total replacement of corn plus variable amounts of soybean meal depending on triticale lysine content in a typical diet formulated to meet 100% of the NRC requirement for lysine for 110 to 240 lb pigs, and representative prices of $5/cwt for corn and $225/ton for 44% protein soybean meal. §Marginal return = [Grain yield × Relative value] — N input cost.