Effect of time of cutting and maceration on nutrient flow, microbial protein synthesis, and digestibility in dual-flow continuous culture1

Abstract

Maceration and evening-cutting are 2 forage management techniques that have independently improved forage quality and nutrient utilization in ruminants, but have not been evaluated in combination. Using a dual-flow continuous culture fermenter system, this preliminary study was designed to evaluate the individual and combined effects of time of cutting and maceration on in vitro ruminal digestion, nutrient flows, and microbial protein synthesis. Forages were harvested as hay from a timothy (Phleum pratense L.)-birdsfoot trefoil (Lotus corniculatus L.) stand in the morning (AM) or evening (PM). Half of each morning- and evening-cut treatment was macerated (AM-M, PM-M). The chemical composition (DM, OM, CP, NDF, ADF), including nonstructural carbohydrates (NSC) and water-soluble carbohydrates (WSC), was determined for each of the 4 treatments (AM, AM-M, PM, PM-M). Forages were ground to 2 mm and allocated to separate fermenters at 60 g of DM/d in a 4 × 4 Latin square design. Fermenters were operated over four 10-d periods with the first 7 d for adaptation followed by 3 d of sampling. Evening-cutting enhanced the apparent digestibility of NDF (P = 0.02) and ADF (P = 0.006), with a tendency (P < 0.10) for improved true DM digestibility and microbial protein synthesis. Molar proportions of individual VFA were not affected (P > 0.10) by time of cutting, though evening-cutting increased (P = 0.02) total concentration of VFA. Maceration had no effect (P > 0.10) on true nutrient digestibility or microbial protein synthesis. An interaction of time of cutting and maceration (P < 0.05) was observed whereby maceration decreased true DM and OM digestibilities in evening-cut treatments, but had no effect in morning-cut treatments. Similarly, maceration reduced total N supply (P < 0.001) and molar proportions of acetate (P = 0.04) and increased molar proportions of propionate (P = 0.01) in evening-cut treatments with no effect on morning-cut treatments. These results indicate that independent use of evening cutting increased fiber digestibility and total VFA concentration, and independent use of maceration shifted molar proportions of VFA toward glucogenic fermentation. The combined use of these management techniques afforded no improvement for in vitro digestibility or metabolism when applied to morning-cut hay, and decreased nutrient digestibility when applied to evening-cut hay. Due to inherent limitations of in vitro systems, the results of this study should be interpreted with caution. Further in vivo studies are needed to support our conclusions.

Nutritional evaluation and ruminal fermentation patterns of kochia compared with alfalfa and orchardgrass hays and ephedra and cheatgrass compared with orchardgrass hay as alternative arid-land forages for beef cattle in two dual-flow continuous culture system experiments1

“…In Exp. 1, the average OM digestibility across treatments was 56%; this finding was consistent with other dualflow in vitro studies, where Cerrato-Sanchez et al (2008) found 52.4% of OM digestibility when fermenters were maintained in a constant 6.4 pH and were fed a diet with 55:45 (DM basis) forage to concentrate ratio, and Kokko et al (2013) reported an average OM digestibility of 56.4% when evaluating the effects of time of cutting and mechanical maceration on birdsfoot trefoil-timothy hay.…”

Diurnal changes in water-soluble carbohydrate concentration in lucerne and tall fescue in autumn and the effects on in vitro fermentation

“…Some studies have revealed that ruminants consume more Medicago sativa, commonly also called lucerne, or tall fescue (Festuca arundinacea) from hays harvested at sunset, in comparison with the same forage harvested at sunrise (Fisher et al 1999(Fisher et al , 2002Burns et al 2005) and this behaviour has been associated with an increase in WSC content. Other studies have associated a higher sugar concentration in the forage with grazing preferences of dairy cows (Horadagoda et al 2009) or with an improvement in N usage (Huntington & Burns 2007) and fibre digestibility (Kokko et al 2013) by the animal. The season can also influence the magnitude of the differences in the concentration of sugars throughout the day (Orr et al 1997;Delagarde et al 2000).…”

Omasal flow of nonstructural carbohydrates and nitrogenous compounds in lactating dairy cows fed diets containing timothy cut in the afternoon or morning

“…Collectively, data from Brito et al (2014) and the current experiment suggest that concentrate supplementation reduced or offset the effects of forage NSC on MPS because MPS increased in studies where high-NSC forage was used without concentrate supplementation (i.e., Lee et al, 2002;Merry et al, 2006;Brito et al, 2009). However, Kokko et al (2013) reported no treatment effect on MPS (mean = 270 mg/d) in dual-flow continuous culture fermentors receiving p.m.-versus a.m.-cut birdsfoot trefoil (Lotus corniculatus L.)-timothy mixed hay without concentrate. We further noted that inclusion of timothy silage diluted the NSC concentration of the forage portion of the diet in our study because silage is more intensively fermented than baleage, which likely contributed to the narrow difference in NSC concentration between the p.m.-and a.m.-cut TIM diets and the lack of effect on MPS.…”