Silage Chop Length and Hay Supplementation on Milk Yield, Chewing Activity, and Ruminal Digestion by Dairy Cows

Abstract

The effects of whole-plant corn silage (CS) particle size and long unprocessed grass hay (LH) supplementation on milk yield, chewing activity, and ruminal digestion in dairy cows were evaluated in 2 experiments. In Experiment 1, corn silage harvested at fine (6 mm; FCS) or coarse (23 mm; CCS) theoretical cut length were fed to 22 lactating Holstein cows. Treatments were 2 total mixed rations containing 58% of dry matter (DM) as FCS or CCS. Diet DM intake tended to be higher in cows fed FCS than those fed CCS (23.4 vs. 22.1 kg/d). However, milk yield and composition, body condition score, and plasma metabolite concentrations were not affected by the dietary treatments. In the second experiment, 5 cannulated Holstein cows were used in a 5 x 5 Latin square design to evaluate the effects of the addition of LH to the diets evaluated in Experiment 1 on chewing activity and ruminal digestion. Treatments were 5 total mixed rations: FCS-based diet plus the addition of 0, 5, or 10% LH (DM basis) and CCS-based diet plus 0 or 5% LH. Long hay addition linearly decreased DM intake in cows fed FCS-based diets (25.0 to 21.7 kg/d), but increased DM intake in those fed CCS-based diets (22.7 to 27.1 kg/d). The intake of neutral detergent fiber (NDF) increased with LH addition in CCS-based diets (7.6 vs. 9.4 kg/d). Rumination time increased (16.8 to 21.0 min/kg of DM intake) when LH was added to FCS-based diets, but it decreased when included in CCS-based diets (18.8 vs. 12.9 min/kg of DM intake). Ruminal pH was higher (5.9 vs. 5.7) and lag-time for in situ NDF disappearance was shorter (3.5 vs. 8.7 h) for cows fed CCS compared with cows fed FCS. The rate of NDF disappearance tended to be higher for the CCS-based diet with 5% LH than for the diet with 0% LH (2.0 vs. 4.4 %/h), but solids passage rate was not affected by the treatments. These results suggest that addition of LH to FCS-based diets does not affect ruminal environment or digestion, but depressed DM intake. In contrast, addition of LH to CCS-based diets may improve ruminal NDF digestion, increasing DM intake by reducing filling effect and time needed for rumination.

Effects of grass hay proportion in a corn silage‐based diet on rumen digesta kinetics and digestibility in dairy cows

“…Considering the results of previous studies (West et al 1997;Couderc et al 2006), the large variation in feed intake with changing the GH proportion was fully expected also in the current experiment when cows were offered diet ad libitum. As the objective of the current experiment was to detect whether the increased addition of GH in the CS-based diet could alter the ruminal passage rate of CS and GH, it was needed to exclude the effect of feed intake on rumen passage rate.…”

“…Recent reports have shown no effect of GH addition on the ruminal passage rate of finely chopped CS in cows fed on CS-based diets supplemented with 5% to 10% GH (Couderc et al 2006;Castro et al 2010). Recent reports have shown no effect of GH addition on the ruminal passage rate of finely chopped CS in cows fed on CS-based diets supplemented with 5% to 10% GH (Couderc et al 2006;Castro et al 2010).…”

Electronic monitoring of rumination activity as an indicator of health status and production traits in high-yielding dairy cows

“…Since chewing activity stimulates the secretion of saliva, which facilitates swallowing and contains high concentrations of bicarbonate and phosphate buffers that aid in buffering and sustaining the ruminal pH at a level suitable for microbial activity, which is physiologically 6.3 to 7.1 (Blikslager et al, 2004). The reduction of forage particle length shortens the time that cattle spend with chewing, increases ruminal acidity and the rate of content passage from the rumen, decreases fibre degradation and milk fat content (Beauchemin et al, 1997;Couderc et al, 2006). Significant differences in the duration of rumination were found between rations; excessive starch and easily fermentable carbohydrates in relation to the content of effective fibre stimulating rumination result in reduced chewing activity.…”

Quantifying body water kinetics and fecal and urinary water output from lactating Holstein dairy cows

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