Date of Graduation

8-2022

Document Type

Thesis

Degree Name

Master of Science in Animal Science (MS)

Degree Level

Graduate

Department

Animal Science

Advisor

Ken Coffey

Committee Member

Beth Kegley

Second Committee Member

Dirk Philipp

Third Committee Member

Christine Nieman

Keywords

Condensed Tannins, Sheep, Tall Fescue

Abstract

Endophyte-infected (Neotyphodium coenophialum) tall fescue, [Schedonorus arundinaceus (Shreb.)] produces ergot alkaloids. Condensed tannins could bind to ergot alkaloids and render them ineffective. The first objective was to improve the health of sheep offered endophyte-infected tall fescue by binding toxins in the rumen with condensed tannins. Non-toxic novel-endophyte infected tall fescue (NE) or toxic endophyte-infected tall fescue forage was harvested, baled at targeted moisture of 55%, wrapped within 8 hours of baling with 2 layers of net wrap and 20 layers of plastic, and ensiled for at least 60 days. Prior to feeding, forages were chopped and packed into plastic trash bins (167 L) lined with 2 plastic bags (3 mil). Non-pregnant, non-lactating ewes (n = 20; 57 ± 1.3 kg initial BW) were housed in individual 1 × 1.5-m pens with metal grate flooring and ambient temperature maintained at 27 to 29 °C. Sheep were offered ad libitum access to either NE or toxic endophyte-infected tall fescue baleage with no condensed tannin (E0), condensed tannin at 10 g/kg DM (E10), or 30 g/kg DM (E30). All ewes received 4 g/kg BW liquid molasses, serving as the carrier for the condensed tannin supplement in E10 and E30. The study consisted of two 21-d periods with a 14-d adaptation followed by 7-d total fecal and urine collection, and a 30-d washout between periods. Dry matter intake (DMI; P < 0.05) was greater for NE than E10 and E30. Dry matter digestibility (DMD; P < 0.05) and OM digestibility (OMD; P < 0.05) were greater for NE than E30. Digestible DMI (P < 0.05) and organic matter intake (OMI; P < 0.05) were greater for NE than treated groups. Prolactin concentrations were greater for ewes offered NE (P <0 .01). Nitrogen retained did not differ among treatments (P ≥ 0.31). The second objective evaluated the effects on forage components and silage fermentation products by ensiling chopped tall fescue with quebracho tannin. Tall fescue was harvested with a Carter harvester at 1000 h, spread on concrete, mixed thoroughly, and dried for 1 or 2 h to achieve 67 and 44% moisture [high moisture (HM) and low moisture (LM), respectively]. Quebracho tannin was either not applied or mixed with distilled water 7 d prior to packaging and applied at 1 and 2% of the total silage DM to both moisture treatments prior to ensiling. Tall fescue and fescue-tannin mixtures were pressed into PVC pipes (10.2 cm × 29.2 cm) to achieve a packing density of 192 kg/m3 and stored at room temperature (23.7 ℃) for 60 d. Sub-samples were removed and analyzed for fermentation parameters and forage chemical components. Pre-ensiled ergovaline was not different across treatments (P ≥ 0.19). Pre-ensiled acid detergent fiber (ADF) and OM were affected by the moisture × tannin interaction (P = 0.01). Pre-ensiled ADF was greatest in LM silages with 1% tannin compared to all other moisture-tannin treatments. Pre-ensiled OM was greatest in HM with 0% tannin compared to HM with 2% tannin and all LM treatments. Changes between pre- and post-ensiled WSC were greater from HM vs. LM (P < 0.05). Final pH was greater in LM silage with 0% and 1% tannin compared to all HM treatments (P < 0.05). Total acids were greatest in HM (P < 0.05) but did not differ (P = 0.54) among tannin treatments. Ammonia concentrations decreased as tannin levels increased (P < 0.05). Condensed tannin inclusion with toxic, tall fescue did not mitigate tall fescue toxicosis in these studies.

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