Effects of fertiliser nitrogen and herbage dry-matter content on herbage intake and digestibility in bullocks

Abstract

SUMMARY1. Two experiments were conducted, the first during May, July and August, 1958, and the second during August 1960. The first experiment measured the intake and digestive efficiency of cattle fed on fresh cut herbage from low-and high-nitrogen manuring treatments with and without irrigation. The second experiment tested the effect of water added to fresh cut herbage on the intake of cattle.2. Rainfall during the summer of the first experiment was high and irrigation had no effect on any of the criteria used.3. Although the dry-matter content of the fresh herbage from the high nitrogen treatment was consistently lower than that from the low nitrogen treatment (16·6% compared with 19·7% on average when free of surface moisture) the dry-matter intake was the same at 1·97 lb. dry matter per 100 lb. live-weight, on both herbages.4. The average digestibility of the high and low nitrogen treated herbage was 77·6% and 75·4%, the difference being significant. No scouring occurred. Digestibility was 78·9% in May, 76·1% in July and 74·5% in August (average of N levels).5. Rain water carried on the leaf surface was shown to have no effect on dry-matter intake.6. It is concluded that the dry-matter intake of cattle feeding on fresh herbage is unlikely to be restricted either by a high internal water content in the herbage or by rain water on the leaf surface.

THE EFFECT OF CUTTING HEIGHT AND NITROGEN LEVEL ON THE YIELD, IN VITRO DIGESTIBILITY AND CHEMICAL COMPOSITION OF ITALIAN RYEGRASS SWARDS

“…The efifect of N on digestibility has been found to be small, according to Dent and Aldrich (6) and Minson, Raymond and Harris (18). However, Holmes and Lang (10) found that the digestibility of a mixed grass/clover sward was significantly increased by increasing the N level from 116 to 410 lb/ac. In contrast, McCarrick and Wilson (16) found that the application of 46 and 92 Ib N/ac reduced the digestibility of mixed swards by 2'15% and 2-33%, compared to swards receiving no N. Barlow (2) also reported a reduction in the digestibility of herbage with increasing N levels.…”

“…The increase in yield of DM ceases to be linear before the yield of herbage N is similarly affected, this being at least partly due to the increased N content of the herbage (22,26). However, herbage digestibility is affected only slightly by N application;, and decreased digestibility (2) and increased digestibility (10) have been reported from increased applications of N. Increasing the frequency of defoliation normally results in lower yields of herbage DM (1,3,20), but digestibility and N content of the herbage are increased (13,19).…”

Performance responses of lambs of various ages to Italian ryegrass (<i>Lolium multiflorum</i>) fertilized with various levels of nitrogen

“…Neither DM content nor dry matter intake of lambs were affected by treatment (Table 1). Holmes & Lang (1963) found that DM intakes were similar for both herbages tested by them, even though the DM content of herbage from their high N fertilization treatment was consistently lower than that from their low N treatment (16.5% vs. 19.7%).…”

Pasture Productivity of Three Swards With and Without Nitrogen Fertilization

“…However, when they are restricted to one or the other herbage treatment, feed consumption is comparable ( 8,9, 1 0 ) . The use of N fertilizer on grass versus the use of legumes to fix atmospheric N has been a controversial topic for many years.…”

“…Apart from the economic considerations and the yield of dry matter per area of land, the efiect on the efficiency of the animal must be considered. Blaser (2) and Holmes and Lang (8) cite several experiments in which output per animal tended to be higher for animals grazirrg grass-legume mixtures compared with N-fertilized grass, possibly because of higher soluble carbohydrates and unknown beneficial effects from the legumes (2). Another explanation is the slower rate of decline in digestibility of white clover compared with grass due to increasing maturity (7).…”