G. F. Wilson

Ingested soil as a source of microelements for grazing animals

Abstract Two sheep were drenched each with 100 g of soil containing approximately 1 mc each of 60Co, 54Mn, 7BSe, and 65Zn. Activities of these isotopes in blood, urine, and faeces were monitored at intervals over a 10-day period by gamma-ray spectroscopy. At the end of this period the animals were killed and a range of hard and soft tissue samples was taken for analysis. From the data obtained on blood and tissue samples taken at time of death, and from urine samples over the 10-day period, amounts of isotopes absorbed by the animals and amounts of isotopes originally held on the ingested soil were compared. The amounts of the isotopes absorbed by the animals from the soil, expressed as a percentage of an isotope held on the soil, were approximately: 75Se, 34 percent; 65Zn, 14 percent; 60Co, 1 percent; 54Mn, 0.4 percent.

Grass tetany. 1. Influence of starch and peanut oil supplements on plasma magnesium, calcium, and phosphorus levels in grazing dairy cows.

Two feeding trials were carried out with lactating cows during early spring (September) and late spring (November). Three groups of animals were used; one received a starch supplement at each milking, the second a peanut oil supplement at each milking, and the third (control) received no supplement. Feed during the experimental periods was ‘Grasslands Ruanui’ perennial ryegrass, with a mineral composition believed to be conducive to hypomagnesaemic tetany. In the first trial plasma magnesium levels of mature animals were markedly lowered on all treatments by feeding Ruanui ryegrass; the effect on young animals was much smaller. No cases of clinical tetany were observed. Depression of plasma magnesium levels was lessened by starch supplementation and increased by oil supplementation. Plasma magnesium and phosphorus levels were positively correlated for individual cow means over the experimental period. Plasma calcium levels lay in the normal physiological range throughout Faecal levels of higher f...

Milk composition as affected by intra-ruminal infusion of volatile fatty acids to cows on a restricted ration.

Abstract Dilute solutions of acetic, propionic, and butyric acids were infused into the rumens of six lactating cows receiving a restricted hay and concentrate ration. Milk yield and composition. characteristics of the butterfat, and concentration of individual volatile fatty acids in the rumen liquor were determined. All three acids raised milk yield (P < 0.05). Increased yields of butterfat (P < 0.10) and solids-not-fat (P < 0.05) were obtained with acetic acid, but the percentage composition was not changed significantly. Propionic acid lowered the daily butterfat yield (P < 0.10) and butterfat percentage (P < 0.05). but increased the protein yield (P < 0.05) and percentage (P < 0.01), and hence increased the level of solids-not-fat in the milk. Butyric acid increased (P < 0.05) the yield and the percentage of butterfat (P < 0.05) and decreased (P < 0.05) the solids-not-fat percentage in the milk. The three acids lowered the iodine values of the butterfat. Butyric acid increased the Reichert value of t...

Ryegrass varieties in relation to dairy cattle performance

Abstract Tetraploid Western Wolths, “Grasslands Paroa”, and “Grasslands Ruanui” perennial ryegrasses were compared in terms of their effects on the yield and composition of milk. A winter and a spring experiment were carried out. During the winter experiment, when groups of Friesian cattle were used, the cows on Western Wolths and Paroa ryegrasses produced a higher yield of milk than those on the Ruanui ryegrass, but the milk from the Western Wolths group was significantly (P < 0.05) lower in butterfat percentage than that from the others. This reduction was associated with a decreased proportion of acetic acid and an increased proportion of propionic acid in the rumen liquor. In the spring experiment, when lactating monozygous twin cattle were used, milk yields and butterfat percentages were similar for the three groups, but the solids-not-fat content of the milk produced by the cows grazing Ruanui ryegrass was significantly depressed (P < 0.01). Possible reasons for the differences in nutritive value of...

DEPOSITS ON RUMEN EPITHELIUM ASSOCIATED WITH INGESTION OF SOIL

Abstract Three groups of newly weaned lambs, housed indoors, were fed respectively: control diet; control diet + 50 g Egmont soil per day; control diet + 50 g Papakauri soil per day. At the end of the lO-week experiment it was found that the rumen epithelium of the control animals was cream or light grey in colour and that of animals receiving soil was dark grey to black. The deposit on the epithelium appeared to be precipitated material rather than particulate matter of soil origin. This dark grey to black deposit noted in animals receiving soil was removed by treatment with 6N HCI and shown to contain P, Ca, Fc, AI, Mg, Mn, and Ti.

Ryegrass varieties in relation to dairy cattle performance. 1. The influence of ryegrass varieties on milk yield and composition.

The influence of three varieties of ryegrass on milk yield and composition was examined using lactating monozygous twin cattle in a series of experiments. During the spring period the mean milk yields produced by the different groups, in decreasing order, were: Manawa ryegrass > Ariki ryegrass > Ruanui ryegrass (P 0.05). In the autumn experiments the cows on the Ruanui ryegrass produced higher milk and butterfat yields than those on the Ariki ryegrass (P < 0.01). Possible reasons for the differences in nutritive value of the ryegrasses are discussed in relation to results of other recent work.

Ryegrass varieties in relation to dairy cattle performance: IV. Milk production from cows grazing ryegrass pastures at two stages of growth and receiving two levels of nitrogen fertiliser

The effects of cows grazing short and long pastures of ‘Grasslands Ruanui’ perennial ryegrass on the yield and composition of the milk were compared in two experiments. The cows grazing short pasture produced significantly more milk in both experiments than those grazing long pasture. The butterfat percentage in the milk from the two groups did not differ, and the solids-not-fat percentage was depressed by the short pasture in the first experiment and by the long pasture in the second. The depression in the solids-not-fat percentage caused by the short pasture in experiment 1 may have been associated with the chemical composition of the pasture, but the depression caused by the long pasture was probably associated with a lowered intake of digestible energy. The effect on milk yield and composition of cows grazing Ruanui ryegrass pastures which had received high and low levels of nitrogen fertiliser was also examined. The milk yields of cows grazing pasture which had received high levels of nitrog...

Responses in dairy calves to mineral supplements

Abstract The oral administration of 15 mg of selenium (sodium selenite) and 200 mg of copper (copper sulphate) to five- to six-months-old dairy calves produced significant (P = 0.01) increases in their rates of growth, recorded over approximately six weeks.

Survey of magnesium content of soils and pastures and incidence of grass tetany in three selected areas of Taranaki

Abstract Results of a survey of the Mg content of representative yellow-brown loam soils in three selected areas of Taranaki are presented and discussed in relation to parent material and altitude. The areas investigated are in Inglewood, Stratford, and Waimate West counties. Factors affecting herbage Mg concentrations are examined and discussed in relation to the observed incidence of grass tetany (hypomagnesaemia) in dairy herds. The overall range found for exchangeable soil Mg contents v/as 0.36–3.35 me./100 g, with values in the Waimate West area generally higher than those in the lnglewood and Stratford areas. An overall trend of decreasing exchangeable soil Mg with increasing altitude was found. Similar ranges of Mg, K, Ca, and N concentrations in mixed pasture, ryegrass, and white clover were found within all three sampling areas. Statistical correlations between plant Mg concentrations and soil chemical properties were highest when the interactive effects of exchangeable soil K and Ca and soil pH ...

Grass tetany: II. Some observations on plasma levels of magnesium, calcium, and phosphorus in dairy cows and sheep grazing ryegrass and white clover pastures

The effect on the plasma levels of magnesium, calcium, and phosphorus of grazing pure Huia white clover and Ariki or Ruanui ryegrass pastures containing different levels of magnesium, calcium, and phosphorus was studied using 7 sets of identical twin cows and 30 yearling Romney wethers. Grazing either the white clover or the ryegrasses had no influence on the plasma levels of calcium and phosphorus. In cattle grazing Huia white clover, magnesium levels were significantly lower (P < 0.01) than those of animals grazing Ruanui ryegrass, even though the clover contained a higher level of magnesium. In contrast, sheep grazing Huia white clover had significantly higher (P < 0.05) plasma magnesium levels than sheep on Ariki ryegrass on the majority of occasions that the animals were sampled. A significant (P << 0.05) pasture species grazed x time of sampling interaction was observed for plasma magnesium levels in grazing sheep. The observed differences in plasma magnesium levels between the white clover...