Production, composition and manufacturing properties of milk from dairy cows fed hay and silages made from either wilted herbage or formaldehyde-treated herbage

Abstract

Hay, normal silage, and silages prepared from herbage either treated with formaldehyde at 0.8% of the dry matter (DM) ('formaldehyde silage') or wilted to 31 % DM ('wilted silage') were all made from grass/clover herbage cut at the same time. Dairy cows were offered the feeds ad libitum together with 4.5 kg of a barley-meatmeal concentrate daily. The chemical composition, digestibility and DM intake of the feeds together with the production, composition and manufacturing properties of the milk were determined. Compared with normal silage, the formaldehyde silage and wilted silage had lower concentrations of total titratable acids, butyric acid and lactic acid. The DM intakes (g day-1kg -0.75 by COWS of normal silage (126.7) and wilted silage (133.7) were higher than those of formaldehyde silage (114.0) and hay (103.6). The yield of milk fat (kg day-1) was greater for the cows offered wilted silage (0.62) and hay (0.62) than for cows offered normal silage (0.58). The yield of milk protein (kg day-1) was greater for the cows offered wilted silage (0.54) and hay (0.54) than for those offered formaldehyde silage (0.50) and normal silage (0.47). The percentages of milk protein and solids not fat, respectively, were greater for the cows offered wilted silage (3.37, 8.83), formaldehyde silage (3.30, 8.83) and hay (3.30, 8.89) than for those offered normal silage (3.1 5, 8.61). No differences were found between treatments in the heat stability characteristics of the milk. However, the milk of cows fed normal silage produced a firmer rennet curd than the milk from cows fed hay, wilted silage or formaldehyde silage. Cows offered normal silage, formaldehyde silage, wilted silage and hay had liveweight gains (kg day-1) of 0.1 6, 0.35, 0.86 and 0.04, respectively. It is concluded that although the milk fat and protein production of cows fed wilted silage and hay were similar, dairy farmers may prefer to feed wilted silage to dairy cows especially in late lactation, because of the ability of the cows to consume more wilted silage and consequently increase liveweight in preparation for the next lactation.