Ruminal fermentation characteristics of goats selectively bred to have greater consumption of juniper foliage
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© 2019 Elsevier B.V. The objective of this study was to determine if ruminal fermentation characteristics differed in goat lines selectively bred for high or low consumption of J. pinchotii foliage. Ten Boer × Spanish-composite bucks (age = 2 yr; initial body weight (BW) = 67.2 ± 4.3 kg) previously selected for high (High; n = 5) or low (LOW; n = 5) juniper consumption selected from each line were subjected to three periods: Period 1, d 0, grazing native range predominated by Juniperus spp; Period 2, d 1 to 26, group fed for ad libitum intake of sorghum × sudan hay; and Period 3, d 27 to 63, indivually fed sorghum × sudan hay at 3% of body weight (BW) and offered fresh J. pinchotii foliage for ad libitum intake. During each period, rumen fluid was evaluated for pH, VFA, ammonia N (NH3-N), and juniper foliage was evaluated for 48-hr true IVDMD (tIVDMD). There was a Selection line × Period interaction observed for total VFA (P < 0.01) explained by a reranking of Total VFA observed in HIGH compared to LOW selection lines in Periods 1 and 3, but the effect was reversed in Period 2. However, total VFA did not differ within any period between HIGH and LOW. During Period 1, rumen fluid from HIGH contained greater (P < 0.05) ruminal isovalerate and tended to have greater ruminal isobutyrate (P = 0.09) and NH3-N (P = 0.07) than LOW. There was a period effect (P < 0.02) for all response variables. When transitioned to a sorghum × sudan hay diet (Period 2), total ruminal VFA concentrations declined 26 and 4% for HIGH and LOW, respectively, and total VFA (P = 0.08) and valerate (P = 0.09) tended to be greater for LOW compared with HIGH. In vitro digestibility of juniper did not differ (P ≥ 0.48), but numerically, digestibility declined 13 and 12% for HIGH and LOW, respectively, from Period 1 to 2. During Period 3, when transitioned to individual pens with ad libitum access to sorghum × sudan hay and juniper foliage, juniper intake did not differ (P = 0.16) with HIGH consuming 1.2 g/kg BW of juniper compared with 0.62 g/kg BW for LOW. No differences were detected (P > 0.05) for VFA, NH3-N, pH, and tIVDMD between HIGH and LOW goats during Period 3. Goats selectively bred for high or low juniper consumption exhibited minor differences in rumen fermentation parameters measured in the current study.
author list (cited authors)
Stewart, W. C., Whitney, T. R., Scholljegerdes, E. J., Waldron, D. F., Walker, J. W., Adams, R. P., & Musser, J.