D. I. H. Jones

The effect of sodium chloride supplementation of a sodium adequate hay on digestion, production and mineral nutrition in sheep

Four groups of six 18-month-old wethers were fed a diet of hay ad libitum with a pelleted ground barley supplement for 70 days. The control group received no further dietary supplements and the sodium content (0·46%) was above that recommended by published standards. Groups 2, 3 and 4 received supplements of sodium chloride, mixed and pelleted with the barley, to provide a final dietary concentration of 1·7, 2·5 and 3·1% sodium respectively. Dry-matter intake, dry organic-matter intake and digestible organic matter in dry matter (DOMD) were significantly reduced (P There were no consistent or significant changes in the serum concentrations of sodium or potassium following sodium chloride supplementation, but serum calcium and magnesium levels were significantly lowered as a result of sodium chloride supplementation. Sodium chloride supplementation improved the apparent availability of sodium, potassium, magnesium and calcium but reduced that of phosphorus and nitrogen. The retention of Na, K, Mg, P and N was lower at the highest sodium intake but Ca retention was higher. Urine volume and excretion of Na, K, Mg, Ca, P and N increased with sodium chloride intake.

Effect of incorporating rolled barley in autumn-cut ryegrass silage on effluent production, silage fermentation and cattle performance

Direct-cut silage was made in mid-October 1985 from established swards of predominantly hybrid ryegrass ( Lolium perenne x Lolium multiflorum ). The crop contained 161 g dry matter/kg and 94 g soluble carbohydrate/kg and was ensiled in bunker silos with (i) no additive (control), (ii), formic acid (5 litres/t) or (iii) addition of 45 kg rolled barley per tonne of grass in silo. The inclusion of barley reduced effluent production to 27 litres/t of ensiled grass compared with 51 litres for the control and 60 litres for the formic acid treatment. Losses of DM in effluent were small but total in-silo DM loss was reduced from 25 % for the control to 11% by formic acid and to 13% by inclusion of barley. DM content of the silage containing barley was 30 g/kg higher than that of the other silages. Silage treated with formic acid contained least ammonia-N, 6% of the total N, compared with 9% in the barley-added silage and 11% in the control. In vivo assessment in sheep gave metabolizable energy values of 98, 10·9 and 11middot;2 MJ/kg for the control, formic and barley silages, respectively; N retention was higher in the formic acid and barley-added silages. The silages were fed ad libitum to beef cattle for 8 weeks, with a daily feed supplement to the control and formic acid groups to equate barley intakes. Silage DM intake was higher for the barley silage, daily live weight gain per animal was similar for the barley-added and formic acid silages ( c . 1 kg), both being higher than the control (0·8 kg). It was concluded that barley inclusion achieved similar improvements in silage quality, in-silo losses and cattle performance to formic acid treatment but with the additional benefit of markedly reducing effluent production.

The ensiling characteristics of different herbage species and varieties

The ensiling characteristics of grasses and of red clover were examined by means of a small scale vacuum silage technique. Eight grasses, comprising three varieties each of perennial ryegrass and cocksfoot and two varieties of timothy, were evaluated after application of two levels of nitrogen fertilizer. Three varieties of red clover were evaluated at two stages of growth with and without sucrose supplementation during ensiling. Perennial ryegrass varieties contained more water soluble carbohydrates than cocksfoot and timothy varieties. At the low level of fertilizer N, silages made from the first cut in mid-May were all well preserved 3 weeks after ensiling. At the high level of fertilizer only perennial ryegrass varieties and S345 cocksfoot were well preserved. After ensiling for 14 weeks perennial ryegrass silages remained well preserved but secondary fermentation in the cocksfoot and timothy varieties resulted in poor preservation. Silages made from the second cut at the end of May were all badly preserved except for silage made from tetraploid ryegrass at the low nitrogen level. Significant correlations were established between the water soluble carbohydrate content of the grasses and the quality of the resulting silage, but herbage dry-matter content and buffering capacity were not significantly correlated with silage quality. The red clover varieties were lower in water soluble carbohydrate and higher in buffering capacity than the grasses. Although the silages from red clover were well preserved they were of high pH. Supplementation with sucrose significantly reduced pH and ammonia content and increased lactic-acid content.

The effect of nitrogen fertilizers on the water-soluble carbohydrate content of grasses

The effect of nitrogenous fertlizers on the watersoluble carbohydrate content of pure grass swards has been studied in three experiments.