The partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea and its effect on the performance, metabolism and digestibility in dairy cows

Abstract

The objectives of the study were to determine the effect of the partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea on the performance, metabolism and whole-tract digestibility in mid-lactation dairy cows. Forty-two Holstein-Friesian dairy cows were allocated to one of three dietary treatments in each of three periods of 5 weeks duration in a Latin square design. Control (C) cows were offered a total mixed ration based on grass and maize silages and straight feeds that included 93 g/kg dry matter (DM) soyabean meal and 61 g/kg DM rapeseed meal. Cows that received either of the other two treatments were offered the same basal ration with the replacement of 28 g/kg DM soyabean and 19 g/kg DM rapeseed meal with either 5 g/kg DM feed grade urea (U) or 5.5 g/kg DM of the slow-release urea (S; Optigen R ; Alltech Inc., Kentucky, USA), with the content of maize silage increasing. There was no effect (P . 0.05) of dietary treatment on DM intake, which averaged 22.5 kg/day. Similarly, there was no effect (P . 0.05) of treatment on daily milk or milk fat yield but there was a trend (P 5 0.09) for cows offered either of the diets containing urea to have a higher milk fat content (average of 40.1 g/kg for U and S v. 38.9 g/kg for C). Milk true protein concentration and yield were not affected by treatment (P . 0.05). Milk yield from forage and N efficiency (g milk N output/g N intake) were highest (P , 0.01) in cows when offered S and lowest in C, with cows receiving U having intermediate values. Cows offered S also tended to have the highest live weight gain (0.38 kg/day) followed by U (0.23 kg/day) and C (0.01 kg/day; P 5 0.07). Plasma urea concentrations were higher (P , 0.05) at 2 and 4 h post feeding in cows when offered U and lowest in C, with animals receiving S having intermediate values. There was no effect (P . 0.05) of treatment on whole-tract digestibility. In conclusion, the partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea can be achieved without affecting milk performance or diet digestibility, with the efficiency of conversion of dietary N into milk being improved when the slow-release urea was fed.

Replacement of grass and maize silages with lucerne silage: effects on performance, milk fatty acid profile and digestibility in Holstein-Friesian dairy cows

“…Alternatively, differences in plasma 3-OHB may reflect a greater production of butyric acid in the rumen, as increased inclusion rates of lucerne have been associated with a greater ruminal concentration of butyrate (Hassanat et al, 2013). Apparent whole-tract digestibility In the current study, the digestibility of DM, OM, NDF and ADF were similar to others that have evaluated the effect of grass, lucerne or maize silage-based diets (Hoffman et al, 1998;Sinclair et al, 2012), although the mean digestibility of NDF and ADF was higher than has been reported in some other studies (e.g. Broderick et al, 2007;Arndt et al, 2015).…”

Reducing dietary protein in dairy cow diets: implications for nitrogen utilization, milk production, welfare and fertility

“…This not only represents a potential environmental hazard, but is costly in feed use. With respect to cost, although there is scope to use alternative less expensive vegetable sources of protein, or non-protein nitrogen (N) sources such as feed grade or slow-release urea formulations (Sinclair et al, 2012) animal 262 and reduced losses of dietary N to the environment necessitates lower protein levels in dairy cow diets. Indeed, it is recognised that the main factor influencing the excretion of N from dairy cows is protein intake, and there is a very strong and positive relationship between manure N output and dietary protein intake (r 2 of 0.9; Yan et al, 2010).…”

Slow-release urea in diets for lactating crossbred cows

“…The urea physically encapsulated by vegetable waxes is aimed at reducing the speed of ammonia release into the rumen (Santos et al, 2011). This type of urea has been tested in some experiments with dairy cows (Galo et al, 2003;Akay et al, 2004;Souza et al, 2010;Santos et al, 2011;Sinclair et al, 2012). However, the efficiency of this product must be evaluated in diets for crossbred cows with average milk yield.…”