The effect of fat supplementation of concentrates on digestion and utilization of energy by productive dairy cows.

Abstract

Two energy balance experiments each used 6 high-yielding dairy cows. In the first, a 3 X 3 Latin square with one replicate, rations were of 7 kg hay and 11 to 14 kg of concentrates having crude protein 251 g and gross energy 17.9 MJ/kg, given alone or with 5% tallow or 5% soya bean oil. Three weeks of adaptation were followed by 10 to 12 days when excreta were collected and gas exchange estimated. Digestibility and metabolizable energy of concentrates and hay were also assessed using wethers fed to maintenance only. Intakes of DM and digestibility of nutrients other than lipid did not differ among treatments with either sheep or cows. There were no apparent differences in rumen fermentation in the one cannulated cow used, and energy loss in urine was also unaffected. Lipid supplement reduced methane loss. Milk yield and milk energy were increased with tallow, with a simultaneous reduction of milk fat and percentage of protein. Soya bean oil reduced the percentage of milk fat and milk energy produced. The second trial, using similar animals and with similar management had a change-over design in which the concentrate was given alone or with 7% tallow. Results confirmed those of trial 1. The effect of level of feeding on the efficiency of utilization of energy is discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Further studies on the effect of fat supplementation of concentrates fed to lactating dairy cows. II. Total digestion and energy utilization.

“…In sheep methane losses also de creased from diet CO to CI. This was also found in sheep and cows in previous trials (van der Honing et al, 1981). Urinary energy losses in cattle were not different between diets.…”

“…Digestibility of crude fat increased with the addition of fat, because the digestibility of the added fat was very high and also because the fraction of endogenous fat excreted in the faeces became a smaller proportion of the fat ingested. These results are in agreement with results obtained earlier (van der Honing et al, 1981), but are conflicting with various other results (Dijkstra, 1969;Buysse, 1962;Cottijn et al, 1971;Devendra & Lewis, 1974).…”

“…Fat intake in our experiments ranged between 1300 and 2000 g/day and falls within that range. The observed high depression in dXL is also reflected in a somewhat higher depression in dE as compared with the depression in 4dm-The high reduction in dXP confirmed ear lier findings (van der Honing et al, 1981). The small reductions found for dXF may at least partly be the result of the low er dxF found with wether sheep fed at maintenance level, because these lower figures were used to estimate the figures for cows.…”

“…The high reduction for dXL is difficult to explain. In earlier experiments (van der Honing et al, 1981) concentrates supplemented with 7 % fat were also fed to dairy cows. In these ex periments reductions of dXL, due to feeding level were much smaller and aver aged 2.0 units.…”

“…The inclusion of fairly large amounts of fat in the diets for dairy cows may cause negative aspects with regard to the digestion of structural carbohydrates. Reports on this aspect are however conflicting (Dijkstra, 1969;Rohr et al, 1978;Palmquist, 1978;van der Honing et al, 1981). Besides, there are some findings which suggest that the inclusion of fats in the diet shifts the site of digestion from the forestomachs towards the intestines (Knight et al, 1978), and that fat influences rumen fermentation patterns (Kowalczyk et al, 1977;Knight et al, 1978).…”