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The effects of traditional endophyte, endophyte-free, and novel endophyte (MaxQ) Jesup tall fescue hay consumption on digestion and nitrogen retention in steers

by Matthews, April Killebrew

Abstract (Summary)
MATTHEWS, APRIL KILLEBREW. The Effects of Traditional Endophyte, Endophyte-free, and Novel Endophyte (MAXQ) Jesup Tall Fescue Hay Consumption on Digestion and Nitrogen Retention in Steers. (Under the direction of Dr. Matthew H. Poore.) A digestion and nitrogen balance trial was conducted to compare the effects of traditional endophyte-infected (E+), endophyte-free (E-), and novel-endophyte (NE) (MaxQ™) Jesup tall fescue (Festuca arundinacea Schreb.) hay on digestion and N retention in steers. Hay composition was as follows: E+ (10.8% CP, 59.9% NDF, 29.4% ADF), E- (11.8% CP, 58.5% NDF, 28.4% ADF), and NE (11.6% CP, 58.6% NDF, 28.3% ADF). Eight Polled Hereford steers (average initial BW ± SD 240 ± 24 kg) were used in a replicated, 3 x 3 Latin square design, with an extra steer allotted to each square. Steers were fed ad libitum for 14 d followed by a 9 d adaptation to a restricted intake (based upon the animal with the lowest ad libitum intake for the square), and a 5 d fecal and urine collection. Endophyteinfected differed from E- and NE (P < 0.01) in ad libitum DMI (4.99 vs 5.64 and 5.67 ± 0.040 kg/d, respectively) and differed (P < 0.005) in ad libitum DMI as a percentage of BW (1.83 vs 2.07 and 2.09 ± 0.024%, respectively). There were no differences among diets during the digestion trial for restricted DMI (4.99 ± 0.055 kg/d), water intake (20.22 ± 1.131 L/d), and urine output (7.40 ± 0.650 L/d). Plasma prolactin concentrations were lower (P < 0.05) for steers on the E+ diet (7.76 ng/ml) versus those on the E- diet (18.57 ng/ml). The plasma prolactin concentrations for the steers on the NE diet (13.14 ng/ml) were not different from those on the E+ or the E- diets. Dry matter digestibility for E+ was lower (P < 0.05) than E- and NE (62.0 vs 67.4 and 66.6 ± 0.95%, respectively). Organic matter digestibility was also lower for endophyte-infected (P = 0.05) compared to E- and NE (64.9 vs 69.4 and 68.6 ± 0.89%, respectively). Neutral detergent fiber, ADF, and cellulose digestibilities were similar among hay types. Crude protein digestibility was higher (P < 0.05) for E- and NE when compared to E+ (54.7 and 53.2 vs 47.4 ± 1.09%, respectively). Nitrogen retention was lower for E+ than E- (P < 0.06) or NE (P < 0.07) (14.4 vs 22.1 or 21.7 ± 1.90 g/d, respectively). Results from this study indicate that E+ tall fescue hay was lower in ad libitum DMI, DM digestibility, and N retention, than NE or E- and hay from NE and E- did not differ for any characteristic evaluation.
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School:North Carolina State University

School Location:USA - North Carolina

Source Type:Master's Thesis

Keywords:north carolina state university

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