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ARS Home » Research » Publications at this Location » Publication #241165
Title: Effect of wheat forage maturity and preservation method on forage chemical composition and performance of growing calves fed mixed diets

Author
item BECK, PAUL - University Of Arkansas
item STEWART, C - University Of Arkansas
item GRAY, H. - University Of Arkansas
item SMITH, J - University Of Arkansas
item Gunter, Stacey

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2009
Publication Date: 11/16/2009
Citation: Beck, P.A., Stewart, C.B., Gray, H.C., Smith, J.L., Gunter, S.A. 2009. Effect of wheat forage maturity and preservation method on forage chemical composition and performance of growing calves fed mixed diets. Journal of Animal Science. 87:4133-4142.

Interpretive Summary: Three 5-acre wheat (Triticum aestivum L) fields were used to test the effects of maturity at harvest (boot vs dough) and preservation method (hay vs silage) on forage yield, composition, and animal performance when fed in mixed diets. Forages were incorporated into four diets in a 2 x 2 factorial arrangement of treatments with hominy feed, soybean hulls, and cottonseed meal as the primary concentrate ingredients. In Experiment 1, diets contained 20% wheat forage (dry matter [DM] basis) and were fed to 96 beef calves (n = 48 steers and 48 heifers, initial body weight = 505 lb) in 12 pens. In Experiment 2, diets contained 40% wheat forage (DM basis) and were fed to beef steers (n = 48, initial body weight = 437 lb) in 12 pens. These diets were also individually fed to 32 calves (Experiment 1, n=16, body weight = 412 lb; Experiment 2, n=16 calves, body weight = 353 lb) to determine DM and neutral detergent fiber digestibility and gastrointestinal tract passage kinetics. Advanced maturity increased DM yield, decreased crude protein concentration and tended to increase non-fiber carbohydrate concentration, but did not affect neutral and acid detergent fiber or total digestible nutrients concentration. Maturity at harvest, preservation method, or their interaction did not affect average daily gain when roughage was fed as 20 or 40% of the diet. When calves were fed the 40% roughage diets, maturity at harvest did not impact DMI or G:F. Calves fed 40% hay diets consumed more feed than calves fed silage diets as a percentage of body weight, but tended to be less efficient. With either 20 or 40% wheat forage diets there were no differences in particulate passage rate, ruminal retention time, or fecal output. Digestibility of DM tended to be greater for silage than hay diets when fed in 20% roughage diets. Dry matter and neutral detergent fiber digestibility of 40% wheat forage diets with forage harvested in boot stage were greater than diets containing forage harvested in dough stage. Forty percent hay diets also tended to have greater DM digestibility and neutral detergent fiber digestibility was greater compared to silage diets. Although differences in performance were not noted in the present experiments, increased maturity at harvest and preservation as silage can cause differences in DM intake and digestibility of low roughage diets.

Technical Abstract: Three 2.4-ha wheat (Triticum aestivum L) fields were used to test the effects of maturity at harvest (boot vs dough) and preservation method (hay vs silage) on forage yield, chemical composition, and animal performance when fed in mixed diets. Forages were incorporated into 4 diets in a 2 x 2 factorial arrangement of treatments with hominy feed, soybean hulls, and cottonseed meal as the primary concentrate ingredients. In Exp. 1 diets contained 20% roughage (DM basis) and were fed to 96 beef calves (n = 48 steers and 48 heifers, initial BW 229 ' 6.0 kg) in 12 pens. In Exp. 2 diets contained 40% roughage (DM basis) and were fed to beef steers (n = 48, initial BW 198 ' 6.8 kg) in 12 pens. These diets were also individually fed to 32 calves (Exp. 1, n=16, BW=187 ' 9.4 kg; Exp. 2, n=16 calves, BW=160 ' 8.2 kg) to determine DM and NDF digestibility and gastrointestinal tract passage kinetics. Advanced maturity increased (P < 0.01) DM yield, decreased (P < 0.01) CP concentration and tended (P = 0.10) to increase non-fiber carbohydrate concentration, but did not affect (P = 0.22) NDF, ADF, or TDN concentration. Maturity at harvest, preservation method, or their interaction did not affect (P = 0.15) ADG when roughage was fed as 20 or 40% of diet. When calves were fed the 40% roughage diets, maturity at harvest did not impact (P = 0.27) DMI or G:F. Calves fed 40% hay diets consumed more feed (P = 0.04) than calves fed silage diets as a percentage of BW, but tended (P = 0.09) to be less efficient. With either 20 or 40% roughage diets there were no differences (P = 0.13) in particulate passage rate, ruminal retention time, or fecal output. Digestibility of DM tended (P = 0.07) to be greater for silage than hay diets when fed in 20% roughage diets. Dry matter and NDF digestibility of 40% roughage diets with forage harvested in boot stage were greater (P < 0.01) than diets containing forage harvested in dough stage. Forty percent hay diets also tended (P = 0.07) to have greater DM digestibility and NDF digestibility was greater (P < 0.01) compared to silage diets. Although differences in performance were not noted in the present experiments, increased maturity at harvest and preservation as silage can cause differences in DMI, and digestibility of DM and NDF in low roughage diets.