Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → États-Unis → 1994 → The nutritional and toxicological consequences of tarbush (Flourensia cernua DC) ingestion by sheep consuming low quality native tobosa grass diets

New Mexico State University (1994)

The nutritional and toxicological consequences of tarbush (Flourensia cernua DC) ingestion by sheep consuming low quality native tobosa grass diets

King, Douglas Wayne

Titre : The nutritional and toxicological consequences of tarbush (Flourensia cernua DC) ingestion by sheep consuming low quality native tobosa grass diets

Auteur : King, Douglas Wayne

Université de soutenance : New Mexico State University

Grade : Doctor of Philosophy (PhD) 1994

Résumé
Tarbush (Flourensia cernua DC) is a common encroaching Chihuahuan Desert shrub. Two trials were conducted to determine nutritional and toxicological consequences of ingestion of pre-bloom tarbush (TB). For trial 1 (28 d), 16 ruminally cannulated sheep (46 kg, ave) were randomly assigned to control (C) 100% tobosa grass (6% CP, dmb) or, tobosa and 10, 20, or 30% whole TB leaves (19% CP, dmb ; 56 mg/g DM soluble phenolics) treatments. At 30%, TB tended (P = 0.0559) and did increase (P = 0.0049) DMI over all except 20% TB during weeks 3 and 4, respectively. Dietary TB did not affect particulate ($P >$ 0.0626) or fluid ($P >$ 0.1221) digesta kinetics. Tobosa DM and NDF in situ disappearances were similar ($P >$ 0.3471) among treatments. All TB N in situ disappearance rates were greater than 5%/h with potentially degraded fractions over 92%. Ruminal ammonia ($P <$ 0.0029) at 6, 8, and 12 h post-feeding and mean total VFA concentrations (P = 0.0064) increased for 30% TB. Butyrate levels were higher ($P <$ 0.0451) for 30% than all except 20% TB at 2 and 6 h post-feeding. Sheep on all treatments lost BW (P = 0.0945) with C losing $-$6 kg. Serum profiles (d 0, 7, 15, and 21) confirmed nutritional stress but did not suggest toxicosis. For trial 2 (21 d) 21 wethers (47 kg, ave) in metabolism crates were assigned similar treatments, or tobosa plus 26% alfalfa (isonitrogenous with 30% TB). Sheep were fed ad libitum for 11 d then restricted (1% of BW) to limit sorting and maintain uniform DMI. Total urine and feces were collected the last 5 d. Apparent DMD was similar (P = 0.2646) among diets. Nitrogen intake increased (P = 0.0043) with higher TB or alfalfa as did urinary N (P = 0.0008) but not fecal N (P = 0.1626). Nitrogen digestibility differed (P = 0.0042 ; SE=3.4) among C (43%), 10% (46%), 20% (50%), 3% (56%), or alfalfa (63%). Nitrogen retention was similar (P = 0.1569) but negative at $-$2.4, $-$2.2, $-$2.8, $-$2.0, and $-$1.5 g/d for C, 10, 20, and 30% TB or alfalfa, respectively. Serum (d 22) and BW losses indicated animals were mobilizing body reserves thus, confounding interpretation. No toxicosis was evident in either trial ; however, TB secondary metabolites did reduce palatability (astringent, aromatic).

Annonce (WorldCat)

Search Oxford Libraries Online (SOLO)

Page publiée le 9 mars 2015, mise à jour le 20 décembre 2019