The effect of feeding animals ad libitum vs. at maintenance level on the in vivo digestibility of mown herbage from two permanent grasslands of different botanical composition

Abstract

The aim of this experiment was to study the effect of feeding level (FL) on the digestibility of unconserved forage obtained from two permanent grasslands cut at three different dates during the first cycle of growth. Forage was offered to Texel sheep (wethers), at maintenance level and at ad libitum level. Differences in voluntary intake (VI) between grasslands were also tested. Organic matter digestibility (OMD) measured at ad libitum level and at VI was 13% higher on harvested forage from grassland rich in forbs (GRF) than grassland rich in grasses (GRG) at early herbage growth stages, but these differences were no longer found at later maturity stages. In GRF, there were no differences for OMD, at either FL at the young growth stages, but at the end of the cycle the OMD obtained at ad libitum level (0Á56) was higher than that at maintenance level (0Á50). However, in GRG, at an early stage of forage maturity, OMD at ad libitum level (0Á67) was lower than that at maintenance level (0Á70), but this difference was no longer found at the end of the growth cycle. In conclusion, the effect of FL on the digestibility of unconserved forage from permanent grasslands depends on the type of grassland. These differences are mainly explained by the different botanical composition of the grassland types.

Relationships between botanical composition, yield and forage quality of permanent grasslands over the first growth cycle

“…Similarly, Andueza et al . () found the same pattern for VI on two different permanent grasslands. In this study, we showed similar patterns, but the novelties are as follows: first, that the grasslands dominated by competitive species preserve their higher forage quality (OMD and VI) compared to grasslands dominated by conservative species despite the sharp decline observed between SS and HS for OMD; secondly, that the trends identified using our database can be generalized to a large range of permanent grasslands.…”

“…Likewise, Andueza et al . () reported important variations in the floristic composition of two botanically different extensively managed permanent grasslands studied at three dates during the first growth cycle in the Massif Central of France. This complexity is the reason why the variability in the feed value of permanent grasslands, and its evolution over the first growth cycle, are still poorly understood.…”

Feed Value of Barn-Dried Hays from Permanent Grassland: A Comparison with Fresh Forage

“…However, poor knowledge of their feed value and the reduced performance obtained when they were compared to seeded forages, such as that provided by Lolium perenne L. grasslands [1], make farmers reluctant to use forages obtained from semi-natural grasslands. The results obtained by Bruinenberg et al (2002) [1], partially disagree to those obtained by Andueza et al (2010) [2] and Andueza et al (2013) [3] which reported a broad variability in digestibility and voluntary intake (VI) of different permanent grasslands at different maturity stages.…”

Digestibility and protein utilization in wethers fed whole-crop barley or grass silages harvested at different maturity stages, with or without protein supplementation1

“…Sheep fed at maintenance level represent a model of ruminant digestion commonly used as the basis for estimation of digestibility in feed evaluation systems and can be considered the best estimate of the intrinsic digestibility value of feed ingredients for ruminants (Stefanska et al, 2008). In vivo digestibility of nutrients is currently determined at either ad libitum or restricted feeding level (Andueza et al, 2013). At ad libitum feed intake digestibility can decrease, as increased feeding level increases the rate of digesta passage from the rumen (Bourquin et al, 1990).…”