|LANGE, MAICHAL - Universidade Federal De Rondonia|
|SILVA, LUIZ - University Of New Hampshire|
|ZAMBON, MAXIMILIANE - Universidade Federal De Rondonia|
|BRITO, ANDRE - University Of New Hampshire|
Submitted to: American Dairy Science Association Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2022
Publication Date: 7/15/2022
Citation: Lange, M.J., Silva, L.H., Soder, K.J., Zambon, M.A., Brito, A. 2022. Effect of alfalfa- or red clover-grass mixtures on dietary energy utilization in lactating dairy cows[abstract]. American Dairy Science Association Proceedings. Pg 1.
Interpretive Summary: No Interpretive Summary is required for this Abstract Only. JLB.
Technical Abstract: Eighteen multiparous and 2 primiparous mid-lactation organic certified Jersey cows were blocked in pairs by DIM or parity and, within pair, assigned to treatments in a randomized complete block design to investigate the effects of legume-grass mixtures on dietary energy utilization. Forages were harvested as baleage, with diets fed as TMR. The botanical composition (DM basis) of second-cut alfalfa-grass (ALF-G) or red clover-grass (RC-G) swards averaged 65 vs. 80% legume, 17 vs. 15% grasses, and 18 vs. 5% weeds, and that of third-cut ALF-G or RC-G averaged 84 vs. 96.5% legume, 3 vs. 2.3% grasses, and 13 vs. 1.2% weeds, respectively. Diets contained (DM basis) 65% second- and third-cut ALF-G or RC-G (32.5% of each cut) and 35% concentrate. The study lasted 9 wk (2-wk covariate) with data and sample collection done at wk 4 and 7. Methane production was measured with a GreenFeed unit. Fecal grab and spot urinary samples were collected at 5 different time points over 3 d. Feeds and feces were analyzed for gross energy (GE) with a bomb calorimeter. Urinary energy, tissue energy, and heat production (HP) were estimated using published equations. Intake of GE, digestible energy (DE), metabolizable energy (ME), and NEL did not differ (P = 0.63) and averaged 93.2, 60.8, 53.5, and 45.7 Mcal/d, respectively. In contrast, fecal energy (35.5 vs. 29.4 Mcal/d) and milk energy (19.7 vs. 18.5 Mcal/d) decreased (P = 0.04) with feeding RC-G vs. ALF-G. Diet by week interactions were observed for urinary energy (P = 0.05) and methane energy (P = 0.03), and trends for HP (P = 0.10) and tissue energy (P = 0.06). Urinary energy, methane energy, and HP decreased during wk 4 in cows fed RC-GR but did no change in wk 7. Tissue energy increased in the RC-G diet in wk 4 and was similar in wk 7. Interactions (P = 0.05) were found for efficiency of energy utilization expressed as ME/DE, milk energy/ME, and HP/ME. During wk 4, ME/DE increased and milk energy/ME and HP/ME decreased with feeding RC-G vs. ALF-G, with no effect of diet in wk 7. Overall, despite similar energy intake, energy utilization and efficiency were affected by diets, particularly during wk 4.