Effects of the Chop Lengths of Alfalfa Silage and Oat Silage on Feed Intake, Milk Production, Feeding Behavior, and Rumen Fermentation of Dairy Cows

Abstract

Effects of chop length (shorter: 6 mm, or longer: 19 mm) of alfalfa silage and oat silage were determined in 16 mid-lactation Holstein cows, 4 of which were rumen cannulated, using a replicated 4 x 4 Latin square design with a 2 x 2 arrangement of treatments. Experimental periods were 21 d long and consisted of 14 d of adaptation and 7 d of sampling. Cows received a total mixed ration containing [dry matter (DM) basis] 42.0% barley grain-based energy supplement, 10% protein supplement, and 24% of DM longer chop or shorter chop alfalfa silage and 24% of DM longer chop or shorter chop oat silage. Rumen pH was measured continuously, and rumen liquid flow rates were determined in rumen-cannulated cows. Feeding behavior was determined by videotaping, and meal patterns were determined by continuously weighing the feed in the bunk of 8 cows. Reducing the chop length of alfalfa silage and oat silage reduced the average geometric particle length from 14.2 to 10.9 mm and from 13.4 to 10.4 mm, respectively. Reducing the alfalfa chop length did not affect feed intake, whereas reducing the oat silage chop length increased DM intake from to 19.4 to 21.2 kg/d. Reducing the chop lengths of alfalfa silage and oat silage chop length did not affect milk production, rumen fermentation, feeding behavior, meal patterns, and blood metabolites. Daily milk yield, milk fat percentage, and milk protein percentage averaged 36.1 kg/d, 3.00%, and 3.16%, respectively, across diets. The low milk fat percentages suggest that the diets induced subacute ruminal acidosis. This was also substantiated by the rumen pH, which was below 5.6 for more than 122 min/d for all diets. The onset of subacute ruminal acidosis despite apparently adequate dietary neutral detergent fiber content and particle size distribution as well as the long duration of chewing might be attributed to sorting against long feed particles.

Effect of harvest time and physical form of alfalfa silage on chewing time and particle size distribution in boli, rumen content and faeces

“…Baumont et al (1990) showed in an experiment with ewes that the eating rate was highest in the beginning of a forage meal. Chopping did not affect rate of eating or mean eating time in agreement with observation in dairy cow fed alfalfa silage (Bhandari et al, 2008) or whole crop barley silage (Beauchemin and Yang, 2005), whereas Deswysen et al (1984) observed a higher rate of eating in heifers fed grass silage due to chopping. The lower proportion of particles retained on the 1 mm sieve size and the lower mode, mean and 95 percentile PL and PW values in swallowed silage boli in cows fed chopped silage (Tables 5 and 6) in combination with no effect of chopping on rate of eating and mean eating time per kg NDF indicate that the masticative activity during intake is not only controlled by the particle size.…”

Effects of feed delivery time on milk production and sorting of dairy cows

“…The dietary contents of neural detergent fibre, non-fibre carbohydrate, and starch do not suggest that the cows were at risk of ruminal acidosis and milk fat depression (National Research Council 2001). However, the average geometrical particle length of the experimental diet in this study was well below the ranges of this particle length of total mixed rations reported by Bhandari et al (2007) (6.7 to 8.5 mm) and by Bhandari et al (2008) (8.6 to 10.9 mm). Krause and Combs (2003) fed a diet with a similar average geometrical dietary particle length (4.2 mm) and a similar grain content compared with the diet used in our study, and observed that feeding this diet to lactating dairy cows, resulted in an average rumen pH of 5.73, a duration of rumen pH below 5.8 of 6.2 h d (1 , and a milk fat content of 2.71%.…”

Desempenho de bovinos de corte alimentados com diferentes forragens e alojados em baias individuais ou coletivas

“…Estudos prévios com vacas leiteiras também reportaram que o maior consumo de MS ocorreu nas primeiras quatro horas após o fornecimento da ração fresca no comedouro (Bhandari et al, 2008, Carvalho et al, 2012 Não houve resposta (P>0,05) da fonte de forragem sobre o PC em todo o período experimental (Tabela 5), reforçando a hipótese de que a fonte de forragem não exerce influência sobre o desempenho animal, desde que os níveis nutricionais das dietas sejam semelhantes. Em outros estudos, o ganho de peso diário e o PC pré-abate também não foram alterados pela fonte de forragem (Fernandes et al, 2007), mesmo quando os níveis de FDN e CNF na dieta à base de SM foram respectivamente menores e maiores em relação à dieta com SC (Roman et al, 2011), o que teoricamente poderia resultar no maior ganho de peso nos animais alimentados com SM.…”