The duration of time that beef cattle are fed a high-grain diet affects feed sorting behavior both before and after acute ruminal acidosis1,2

Abstract

The objective of this study was to determine how duration of time that cattle are fed a high-grain diet affects feed sorting, both before and after an episode of acute ruminal acidosis. Sixteen Angus heifers (261 ± 6.1 kg; BW ± SEM) were assigned to 1 of 4 blocks and fed a backgrounding (BG) diet (60% forage, DM basis). Within block, heifers were randomly assigned to 1 of 2 treatments differing in days fed a high-grain (HG; 9% forage, DM basis, fed ad libitum) diet before a ruminal acidosis challenge: 34 d for long adapted (LA) and 8 d for short adapted (SA). Ruminal acidosis was induced by restricting feed to 50% of DMI as a proportion of BW (determined individually for each heifer) for 24 h followed by an intraruminal infusion of ground barley at 10% of DMI as a proportion of BW measured before feed restriction. Feed and orts were sampled during the BG period, the first 26 d on the HG diet (only for LA cattle), the 8-d baseline (BASE) period, on the day of the ruminal acidosis challenge (CH), and during 2 consecutive 8-d recovery periods (REC1 and REC2) for each heifer and subjected to particle size analysis: 19-mm (long), 8-mm (medium), and 1.18-mm (short) screens and a pan (fine). On the BG diet, sorting for medium particles tended to be greater (104.2 vs. 102.1%; P = 0.07) for LA heifers than SA heifers, while sorting against short particles was greater (98.2 vs. 100.0%; P = 0.05) for LA heifers. During the first 26 d on the HG diet, LA cattle sorted for (P < 0.001) long (118.8%), medium (117.8%), and short (104.1%) particles and sorted against (P < 0.001) fine particles (45.3%). This sorting pattern was consistent for LA heifers during BASE period, CH day, and recovery periods, across which SA heifers exhibited less sorting (P ≤ 0.1). Greater duration of pH < 5.5 during the BASE period was associated with greater sorting for long particles (R(2) = 0.75, P = 0.01) in LA heifers and for long (R(2) = 0.49, P = 0.05) and medium (R(2) = 0.88, P < 0.001) particles in SA heifers. Long-adapted heifers linearly increased the extent of sorting for long (P = 0.007) and medium (P < 0.001) particles and against fine particles (P = 0.05) during the days following the challenge to a greater extent than SA heifers. Overall, the results demonstrate that longer-term exposure of beef heifers to a HG diet, which caused persistent low rumen pH, influenced feed sorting of heifers, both before and after an induced bout of acute ruminal acidosis, in a manner that would help attenuate the effects of acidosis.

Domestic cattle (Bos taurus taurus) are motivated to obtain forage and demonstrate contrafreeloading

“…In our study, the short latency heifers showed to approach the gate could, in part, be explained by consuming the high-energy, low-roughage diet for 30 d before data collection. Indeed, more experience (34 vs. 8 d) with this type of diet results in greater sorting for longer, fibrous particles [ 7 ]. These responses perhaps reflect a more persistent change in internal state [ 29 ], and future work could examine whether the latency to obtain forage depends on the amount of experience with a high-energy, low-roughage diet, as well as how this relates to patterns of rumen pH within and across days.…”

“…Researchers previously found that heifers with more experience (34 vs. 8 d) with a high-concentrate, low-roughage diet show greater sorting for longer feed particles [ 7 ]. Therefore, to minimize possible changes in feeding behavior during data collection, heifers were fed their assigned treatment diet for at least 30 d beforehand while group-housed at the UC Davis feedlot.…”

“…In contrast, highly fermentable grain-based diets can cause excessive acid production in the rumen, leading to acute or subacute ruminal acidosis [ 4 – 6 ]. When given the opportunity, cattle experiencing ruminal acidosis make diet choices that ameliorate low rumen pH: they preferentially sort for longer feed particles [ 7 – 9 ] and prefer alfalfa in the form of long-stemmed hay rather than pellets [ 10 ].…”

Effect of pelleted cereal-based feed used in the diet on feed intake, eating behaviour, rumination and nutrient digestibility in antelope sitatunga (<i>Tragelaphus spekii</i>)

“…So, further studies are needed to describe the importance of expressing selective intake of diet components by sitatunga. It has been shown that ruminants try to overcome the negative consequences of a sudden drop in rumen pH by selective consumption of structured components and increased saliva production shortly after an episode of rumen acidosis (Schwaiger et al, 2013;DeVries et al, 2014), which may also indicate a higher probability of rumen acidosis when pelleted feed was used in the basal diet. On the one hand, faster eating rate of pelleted diet may increase the probability of rumen acidosis, but on the other, depending on feed processing prior to pelleting and feed composition, pelleted feed may decrease the ruminal OM digestibility, due to faster rumen escape (Górka et al, 2015), and in consequence decreases short-chain fatty acids production in the rumen.…”

Short communication: Risk of subacute ruminal acidosis affects the feed sorting behavior and milk production of early lactation cows

“…When experiencing an acute bout of ruminal acidosis, cows have been shown to sort in favor of the physically effective portion of the diet to alleviate the symptoms of low rumen pH, likely as a result of postingestive feedback (DeVries et al, 2008). Beef cattle have similarly been shown to sort in favor of the longest dietary particles when induced with an acute bout of ruminal acidosis (DeVries et al, 2014a), with those animals experiencing the greatest degree of acidosis demonstrating the greatest selection for long, fibrous particles (DeVries et al, 2014b). To further support the theory that dairy cows alter their preferences when experiencing SARA, Maulfair et al (2013) found that dairy cows experiencing an acidosis challenge selected in favor of a diet that was more physically effective and had lower starch fermentability.…”