Alfalfa Cut at Sundown and Harvested as Baleage Improves Milk Yield of Late-Lactation Dairy Cows

Abstract

Alfalfa (Medicago sativa L.) cut at sundown has been shown to contain greater concentration of total nonstructural carbohydrates (TNC) than that cut at sunup. Fourteen multiparous (8 ruminally cannulated) and 2 primiparous lactating dairy cows were randomly assigned to 2 treatments in a crossover design (2 periods of 24 d) to investigate the effects of alfalfa daytime cutting management on ruminal metabolism, nutrient digestibility, N balance, and milk yield. Half of each alfalfa field (total of 3 fields) was cut at sundown (PM) after a sunny day, whereas the second half was cut at sunup (AM) on the following day. Both PM and AM cuts were field-wilted and harvested as baleage (531 +/- 15.0 g of dry matter/kg of fresh matter). Bales (PM and AM) were ranked according to their concentrations of TNC, paired, and each pair of PM and AM baleages was then assigned to each experimental day (total of 48 d). The difference in TNC concentration between PM and AM baleages fed during the 10 d of data and sample collection varied from -10 to 50 g/kg of dry matter. Each pair of baleage was fed ad libitum to cows once daily with no concentrate. Ruminal molar proportion of acetate and total volatile fatty acid concentration were greater in animals fed the AM baleage, whereas the proportion of valerate was greater with PM baleage; no other significant changes in ruminal molar proportions of volatile fatty acids were observed between forage treatments. Digestible organic matter intake, organic matter digestibility, and plasma Lys concentration were significantly greater in cows fed PM alfalfa, suggesting that more nutrients were available for milk synthesis. Significantly lower body weight gain and retained N as a proportion of N intake were observed in cows fed PM alfalfa, thus suggesting that nutrients were channeled to milk synthesis rather than to body reserves. Intake of dry matter (+1.0 kg/d), and yields of milk (+1.0 kg/d), milk fat (+70 g/d), and milk protein (+40 g/d) were significantly greater in cows fed PM vs. AM alfalfa. Concentration of milk urea N and excretion of urea N as a proportion of total urinary N were significantly reduced, and milk N efficiency was increased when feeding PM vs. AM alfalfa, indicating an improvement in N utilization. Increasing the TNC concentration of alfalfa by shifting forage cutting from sunup to sundown improved N utilization and milk production in late-lactation dairy cows.

Diurnal Leaf Starch Content: An Orphan Trait in Forage Legumes

“…This higher NSC content was primarily attributed to higher starch concentration. The higher NSC content from the evening cutting resulted in higher digestibility, and when evening cut forage was fed to dairy cows, they produced up to 5% more milk compared to the morning cut [47,48]. Breeding for traits, such as diurnally independent starch turnover, as seen in TpDIST27 and TpDIST31 genotypes, would increase the harvestable starch content.…”

Effects of dietary total non-structural carbohydrates and folic acid and vitamin B12 supplement on growth and meat quality of yearling steers in a forage-based beef production system

“…(1 in the afternoon alfalfa in the Brito et al (2008) study whereas in the present study, WSC concentrations were very similar for both treatments in the pasture grass (89.3 g kg (1 for low TNC vs. 96.8 g kg…”

“…(1 reported by Brito et al (2008). During phase 3, the difference in WSC concentrations between the two silages was 14 g kg (1 .…”

“…Preynat et al (2009b) also reported that a combined supplement of folic acid and vitamin B 12 tended to increase milk production in dairy cows during the first 16 wk of lactation. Brito et al (2008) observed that late-lactation dairy cows fed alfalfa silage prepared from forage cut in the afternoon produced 1 kg d…”

Effect of glycerol in combination with alfalfa on in vitro gas production and microbial protein synthesis

“…Studies have been conducted to verify if the NSC contents of alfalfa can improve nitrogen utilization (Brito et al 2008(Brito et al , 2009. Results from these studies shows that HNSC does improve a number of fermentation parameters as compared with LNSC.…”