Effects of Alfalfa Particle Size and Specific Gravity on Chewing Activity, Digestibility, and Performance of Holstein Dairy Cows

Abstract

Two experiments were carried out to test the effects of alfalfa particle size and functional specific gravity (FSG) on chewing activity, digestibility, rumen kinetics, and production of lactating dairy cows fed corn silage based rations. In experiment 1, water-holding capacity (WHC), insoluble dry matter, hydration rate, and FSG changes were determined in alfalfa hay (varying in particle size) and corn silage. Reduction of particle size increased bulk density, FSG, and the rate of hydration, and decreased WHC of alfalfa. In experiment 2, 9 midlactation Holstein dairy cows fed total mixed rations containing 3 sizes of alfalfa hay (with geometric mean 7.83, 4.04, and 1.14 mm) were used in a replicated 3 x 3 Latin square design. The diets contained 20, 20, 35, 7, 7.5, 10, 0.3, 0.1, and 0.1% of DM alfalfa, corn silage, barley, soybean meal, beet pulp, wheat bran, dicalcium phosphate, vitamin premix, and salt, respectively. The geometric means (GM) of rations were 3.34, 2.47, and 1.66 mm in long, medium, and fine alfalfa treatments, respectively. Reduction of particle size increased daily NDF intake (kg), but decreased the proportion of physically effective factor (pef) and physically effective NDF (peNDF) in the ingested rations. Reduction of particle size increased the FSG of rations and intake of DM but reduced digestibility of NDF and ash. Reduction of particle size decreased ruminal mean retention time (RMRT), but increased the ruminal particulate passage rate. Milk and FCM yield were not affected by treatments. The rumen pH, total chewing activity, rumination, eating time, and milk fat were reduced as particle size decreased, but milk protein increased. This study showed that reduction of forage particle size increased bulk density, FSG, and hydration rate of alfalfa and was the most influential factor affecting DMI, milk composition, and chewing behavior. Reduction of forage particle size had minimal impact on digestibility and milk production.

Rumen fermentation, blood metabolites, and growth performance of calves during transition from liquid to solid feed: Effects of dietary level and particle size of alfalfa hay

“…Krause et al (2002) reported that mean ruminal pH was positively correlated with the time spent on ruminating and chewing. Our results concerning forage PS are in agreement with those of other authors (Krause et al, 2002;Teimouri Yansari et al, 2004), confirming that forage PS plays a major role in maintaining opti- Gain-to-feed ratio was calculated by dividing ADG (g) by average daily DMI.…”

Effects of different sources of carbohydrates on intake, digestibility, chewing, and performance of Holstein dairy cows

“…This finding was confirmed by Mansfield et al [31], but was in contrast to the findings of Valk et al [22]. In contrast to the current experiment, a lower intake of CP, lower NH 3 -N concentrations in the rumen, and lower CP degradability for cows fed on BP was observed, compared with that in cows fed on corn [20] or barley [33]. The consumption of carbohydrates such as NDSC that are more extensively fermented in the rumen may improve the utilization of the NPN through the stimulation of microbial protein synthesis.…”

“…Therefore, compared with barley, BP created more favorable conditions for microbial utilization of other carbohydrates in the rumen, at least in part due to the neutral pH. Decreasing daily mean ruminal pH, which was associated with an increase in ruminal outflow rate of digesta, resulted in a decrease in ruminal NDF digestibility and total tract digestibility [2,8,9,33]. Zebeli et al [9] showed a decrease in total tract NDF digestibility by increasing the outflow rate of particulate digesta, which was associated with a decrease in ruminal mat consistency.…”

A meta-analysis and meta-regression of the effect of forage particle size, level, source, and preservation method on feed intake, nutrient digestibility, and performance in dairy cows

“…In agreement with our findings, Kowsar et al (2008) reported an increased in DM digestibility when fine particle of alfalfa hay was added to corn silagebased diet. The improvement in milk production with decreasing FPS in our study is interesting because previous research studies (Kononoff and Heinrichs, 2003a;Teimouri Yansari et al, 2004;Alamouti et al, 2009) and review articles , as well as meta-analyses (Zebeli et al, 2006;Tafaj et al, 2007), uniformly indicated no significant effect of FPS on milk production, although DMI was mostly improved in all these studies. In the current meta-analysis, we used a large number of experimental findings and a more precise statistical approach, which was able to detect even marginal effects of FPS.…”