Effects of a Nonforage Diet on Milk Production, Energy, and Nitrogen Metabolism in Dairy Goats throughout Lactation

Abstract

The objective of the experiment was to compare a silage-based control diet (C) with a nonforage diet (NF) in dairy goats throughout lactation in terms of animal performance and energy utilization. Eight Saanen goats were divided into two groups and fed C or NF, a commercial blend that included sunflower meal, cassava, coconut meal, and whole cottonseeds as the main ingredients that was characterized by a small particle size and a high crude protein content. In early, mid, and late lactation (44, 100, and 219 days in milk) the goats were individually tested for dry matter intake (DMI), digestibility, milk yield and composition, milk renneting properties, rumen and plasma parameters, and nitrogen and energy utilization (open circuit respiration chambers). During early and mid lactation, the NF fed goats had a very high DMI: 2946 and 2915 g/d, respectively. Nevertheless, milk yield was similar for the two treatments: 4369 vs. 4342 and 3882 vs. 3841 g/d for goats fed diets C and NF during the first and second periods, respectively. Milk fat content was not statistically different between the two diets. The protein content and rheological parameters of milk were similar for the two diets. Nonprotein nitrogen and urea levels in milk of goats fed NF were significantly higher than goats fed C. Ruminal ammonia and plasma urea nitrogen were also significantly increased by diet NF, due to its high protein content. Plasma glucose, beta-hydroxybutyrate, and nonesterified fatty acids and ruminal volatile fatty acids were not influenced by dietary treatment. Dietary NF significantly decreased energy digestibility (74.5 vs. 65.8%, on average for the lactation, for C and NF, respectively) and had a significantly lower metabolizability (metabolizable energy/intake energy; 66.6 vs 58.0%, on average); however, the efficiency of utilization of metabolizable energy was unaffected by the diet. In conclusion, goats were fed a nonforage diet during the entire lactation without detrimental effect on their health and productive performance.

Relationship between milk urea, blood plasma urea and body condition score in primiparous browsing goats with different milk yield level

“…This test measured the total degree of linear relationship between BCS and daily milk yield within each level, despite of the individual stage of lactation. Means of milk urea were similar to those by Bava et al (2001) for Saanen goats, with higher milk yield and lower milk protein content. However, the present data were lower than those by Sahoo & Walli (2008) for crossbred goats and by Cabiddu et al (1999) for Corsican goats fed exclusively pasture.…”

“…Indeed, protein can be produced in the rumen from urea and other nitrogen sources and the flow of urea is from the rumen to the blood and vice versa (Harmeyer & Martens 1980, Cunningham 2002. Plasma urea is positively correlated to milk urea in cows (Roseler et al 1993, Butler et al 1996, Broderick & Clayton 1997, sheep (Cannas et al 1998) and goats (Cabiddu et al 1999, Bava et al 2001, Sahoo & Walli 2008. Given that milk is easier to collect than blood, milk urea is a suitable parameter to evaluate urea metabolism, especially on a herd level (Schepers & Meijer 1998), both in intensive and extensive dairy farms.…”

Efficiency of endogenous urea ¹⁵N nitrogen incorporation into bacterial and milk protein of goats fed diets with three different protein levels

“…However Bava et al (2001) reported higher levels of urea in milk than in plasma, but also a positive correlation between these values. The content of ammonia in rumen fluid (Table 4) differed highly between the diets (P<0.01).…”

Inclusão de diferentes níveis do resíduo de feijão nas rações de ovinos sobre o consumo e digestibilidade dos nutrientes

“…However, studying diets without forages in goat feeding, Bava et al (2001) observed lower digestibility coefficients for the diets containing the highest levels of forage. These authors attributed this effect of the digestibility coefficient to a higher passage rate of the diets without forages, i.e., with a higher amount of easily-fermentable carbohydrates (concentrate).…”