No abstract

Metabolism studies were carried out with 45 kg pigs to examine barley meal from the varieties Golden Promise, Maris Mink, Lami, Zephyr and Abacus, all with similar nitrogen (N) content, and barley meal from the variety Zephyr which had received four different levels of N fertilisation. There were no significant differences (P> 0.05) between varieties for the apparent digestibility coefficients of gross energy (GE) and proximate constituents. the least significant difference for GE and N being 0.025 and 0.089 of the respective means. The mean digestible energy (DE) and metabolisable energy (ME) values were 14.48 and 14.07 MJ/kg dry matter (DM). The mean apparent digestibility of N was 0.685. The apparent digestibility coefficients of G E and N of meal from the variety Zephyr increased with N content. The increase in DE value with N content could be attributed to the increase in N digestibility.

1. Twenty-four pigs (mean body-weight 44 kg) were used to determine the digestibilities of energy, nitrogen and amino acids in dried microbial cells (DMC) grown on methanol and in white fish meal (WFM). N utilization and the excretion of various nitrogenous compounds were also studied. 2. Semi-purified diets containing DMC, WFM or no protein source were offered at the rate of 1 kg fresh food/d. Daily N intakes were 26-5, 24-7 and 0-65 g respectively. 3. Mean metabolic faecal N determined with the protein-free diet was 1-11 g/d (1-26 g/kg dry matter (DM) eaten) for the two experiments. The corresponding endogenous urinary N value was 2-91 g/d. 4. Daily urinary N output of pigs given the diet with WFM was significantly greater than that of pigs given the diet with DMC, with the result that N retention, net protein utilization and biological value were higher for pigs given DMC. 5. Apparent and true digestibility of amino acids were higher for the diet with DMC than for the diet with WFM. 6. N excretion in the form of ammonia, urea, uric acid and allantoin accounted for 81, 91 and 99% of the total N excreted by the groups given the protein-free diet, DMC and WFM respectively. Pigs given DMC excreted greater quantities of allantoin-N and less urea-N than pigs given WFM.

No abstract

The digestibility of nutrients in milk replacers were determined with Ayrshire bull calves from 7 to 28 days of age. The mean apparent digestibilities of dry matter (DM), gross energy (g.e.) and nitrogen declined from 0.84 to 0.79; 0.85 to 0.78 and 0.79 to 0.76 when cooked potato flour replaced an equivalent weight of spray-dried whey in liquid diets. Potato starch has a mean apparent digestibility of 0.65. Nitrogen retention was unaffected by diet, but the potato diet had a lower metabolisable energy value than the control diet (15.6 and 17.5 MJ per kg DM respectively). Glucose levels in the jugular blood were lower for calves fed the potato based milk replacer. The apparent digestibilities of dry matter, gross energy and nitrogen showed marked improvements with age, particularly on the potato based diet, with starch digestibility improving from 0.50 to 0.74 between 10 and 24 days. While blood glucose concentration increases with age, the relative differences between treatments remained.