The effect of date of cut and barley substitution on gain and on the efficiency of utilization of grass silage by growing cattle

Abstract

1. The effect of harvesting date of perennial ryegrass (Lolium perenne) on the nutritive value of the resultant silage and the effect of substitution of late-cut silage with barley was examined in growing cattle. The diets comprised early-cut (H) and late-cut (L) silage offered alone or with 280 (LCI) or 560 (LC2) g rolled barley/kg total dry matter (DM) substituted for late-cut silage.2. Both silages were prepared with the addition of formic acid (850 g/l; 2.4 litres/t fresh weight) to a partially wilted crop, and were judged to be well fermented (pH 3.9,3.8) with lactic acid contents of 108 and 73 g/kg DM, total nitrogen contents of 24.6 and 18.4 g/kg DM and ammonia-N contents of 121 and 124 g/kg total N (values for early-and late-cut silages respectively).3. Two experiments were conducted to measure duodenal non-NH,-N (NAN) supply in relation to N intake on the four diets (feeding level 18 g DM/kg live weight (LW)) and to examine the partition of the metabolizable energy (ME) supply from the four diets using open-circuit indirect calorimetry (three feeding levels, 14, 17 and 20 g DM/kg LW). The experiments were undertaken with eight and nine Friesian male castrates respectively with a mean starting weight of 300 kg and age 12 months. The animals used in Expt 1 had been previously fitted with cannulas into the dorsal rumen and the proximal duodenum.4. NAN supply was significantly higher on diet H than all other diets which were similar irrespective of the level of barley inclusion. Mean ME contents (MJ/kg DM) of the two silages differed markedly (H 11.9, L 9.7) and barley addition (LCI and LC2) restored values to 10.7 and 11.1 MJ/kg DM respectively. Estimated NAN absorption in relation to energy supply was significantly higher for diet H (1.47 g/MJ ME) than for all other diets (mean 1.25 g/MJ ME).5. Partition of ME supply using conventional linear analysis indicated dietary differences with respect to estimated ME for maintenance (L H, LCI and LC2) and efficiency of utilization of ME supplied above maintenance (L > H, LCI and LC2), but difficulties in biological interpretation of these findings led to the use of exponential curve analysis. This provided an improved description of the findings, and whilst dietary differences were apparent, none were statistically significant. It was concluded that a single exponential equation could be used satisfactorily to describe all values.6. The consequence of these findings in relation to the carcass retentions of energy. fat and protein reported by Thomas ef al. (1988) is discussed and possible reasons for the discrepancies in energy retention measured by comparative slaughter balance and open-circuit indirect calorimetry are considered.In the previous paper (Thomas et al. 1988) the consequence of delaying the harvesting of grass for ensiling on the nutritive value of the resultant silage when offered to beef cattle was examined, and the response to barley substitution of the later-cut material was quantified. That study was concerned with the examination of body and ...

Energy components of growth in Holstein steers fed formaldehyde- and formic acid-treated alfalfa or orchardgrass silages at equalized intakes of dry matter.

“…Our results are consistent with those of Beever et al (1988), who concluded that reduced dietary fiber concentration is a very important factor increasing partial energetic efficiency as concentrate supplementation is used. Van Soest (1965) found that legumes had a smaller fraction of NDF than grasses.…”

Effect of grain- or by-product-based concentrate fed with early- or late-harvested first-cut grass silage on dairy cow performance

“…For instance, if OMD were overestimated by 40 g/kg in comparison with the value reported by Kuoppala et al (2010), who determined digestibility by the total feces collection method in cows fed similar diets (comparable silage iNDF), then urinary energy excretion would be on average 7.7% lower. However the difference in urinary energy excretion between early and late cut silage was greater in this study than reported for lactating cows by Gordon et al (1995), who observed 77.4% greater energy output in urine with highly digestible silage, and in growing cattle by Beever et al (1988), who recorded 18.2% greater energy output in urine with highly digestible silage.…”

Methane production, rumen fermentation, and diet digestibility of Holstein and Jersey dairy cows being divergent in residual feed intake and fed at 2 forage-to-concentrate ratios

“…A well-known methane mitigation strategy is to increase proportions of concentrate in the diet of dairy cows, especially above 35 to 40% of the diet (Sauvant and Giger-Reverdin, 2009), although exceptions occur where methane emissions have been increased (Beever et al, 1988). In the current study, methane production, regardless of the expression, was lowered in response to the HC diet (Table 5) with largest declines for Holstein cows.…”