Effect of crabgrass (Digitaria ciliaris) hay harvest interval on forage quality and performance of growing calves fed mixed diets

• Published in: Journal of animal science 2007-02, Vol.85 (2), p.527-535
• Main Authors: Beck, P.A, Hutchison, S, Stewart, C.B, Shockey, J.D, Gunter, S.A
• Format: Article
• Language: English
• Subjects: acid detergent fiber; ad libitum feeding; Animal Feed - analysis; Animal Feed - standards; Animal Nutritional Physiological Phenomena; Animal productions; Animals; beef cattle; Biological and medical sciences; calf feeding; calves; Cattle - growth & development; Cattle - physiology; crude protein; Diet - veterinary; digestibility; Digestion - physiology; Digitaria - chemistry; Digitaria - growth & development; Digitaria - metabolism; Digitaria ciliaris; Feed and pet food industries; feed conversion; feed intake; feed rations; Female; Food industries; forage crops; forage grasses; forage quality; Fundamental and applied biological sciences. Psychology; gastrointestinal transit; harvest date; hay; liveweight gain; Male; neutral detergent fiber; nutritive value; phenology; Random Allocation; rumen; soybean hulls; temporal variation; Terrestrial animal productions; Time Factors; Vertebrates; Weight Gain - physiology
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jas.2006-358

Twelve 0.81-ha crabgrass (Digitaria ciliaris [Retz.] Koel.) hay fields were harvested at 21, 35, and 49 d of regrowth (average phonological growth stage of 30, 51, and 56, respectively). Increased harvest interval exhibited a linear decrease (P < 0.01) in CP (14.1, 13.7, and 10.6% of DM, respectively) and increase (P < 0.01) in NDF (65.3, 70.6, and 70.2% of DM, respectively) and ADF (35.7, 38.9, and 42.7% of DM, respectively). Hays were incorporated into 3 diets that contained 20% (DM basis) crabgrass hay, ground corn (33%), and soybean hulls (32%). Diets contained 14.4, 14.4, and 13.6% CP; 1.83, 1.72, and 1.81 Mcal of NEm/kg; and 1.21, 1.10, and 1.17 Mcal of NEg/kg; respectively. Diets were fed to beef calves in 12 pens at a rate of 2.3% (DM basis) of BW in 1 experiment (n = 120, initial BW 210 ± 4.4 kg) and ad libitum in another experiment (n = 60, initial BW 207 ± 4.4 kg). To measure passage rate of the hay and concentrate portions of the diets, 12 heifer calves (BW = 145 ± 4.5 kg) were individually fed at 2.3% of BW for 14 d and dosed with Dy-labeled soybean hulls and Yb-labeled hay. In situ DM digestibility of the hays and diets were determined using 3 ruminally cannulated steers (BW = 584 ± 10.4 kg). Harvest interval did not affect (P >= 0.11) ADG of limit-fed calves during the diet acclimation or growing phases (average 0.32 and 0.80 kg, respectively) or ADG of calves fed ad libitum (average 1.21 kg). Dry matter intake of calves fed ad libitum averaged 7.9 kg/d (3.28% of BW) and was not affected (P >= 0.22) by harvest interval. Gain:feed was not affected (P >= 0.20) by harvest interval (0.13 and 0.15 for limit-fed and ad libitum-fed calves, respectively). Increased harvest interval linearly increased (P < 0.01) ruminal retention time of the hay and tended (P = 0.06) to linearly increase ruminal retention time of the concentrate portions of the diet. Harvest interval linearly decreased (P = 0.35). In the conditions of this study, increasing harvest interval of crabgrass hay from 21 to 49 d had no deleterious impact on animal performance or efficiency of gain when fed to growing calves in a high-concentrate mixture.