Effect of maturity stage and chopping length of maize silage on particle size reduction in dairy cows

Abstract

-The effects of maturity stage and chopping length of maize silage on chewing behaviour, particle size reduction and rumen retention time were studied in four lactating cows fitted with a ruminal cannula, according to a 4 × 4 Latin square design. Maize silage made up 80% of the diet and the cows were fed at 90% of the ad libitum intake level. Chopping length had only a significant effect on the particle size of the maize harvested at the late maturity stage. For the latter, the proportion of particles larger than 2 mm (LP2) from the feed to the rumen content decreased from 73 to 38% for the coarse maize and from 58 to 37% for the fine maize, mainly by ingestive mastication. Eating time expressed per unit of feed intake did not vary significantly between these two silages (21.3 vs. 19.8 min·kg -1 DMI). Ingestive mastication in dairy cows thus reduces long particles more efficiently than short particles.particle size / chewing behaviour / maize silage / dairy cows Résumé -Effet du stade de maturité et de la finesse de hachage de l'ensilage de maïs sur le comportement alimentaire et la réduction de la taille des particules chez les vaches laitières. Quatre vaches laitières canulées du rumen ont reçu en quantités limitées et dans un dispositif en carré latin 4 × 4, quatre ensilages de maïs qui différaient par leur finesse de hachage et leur stade de maturité. La ration était composée de 80 % d'ensilage et 20 % de concentré. Les différences de taille de particules des ensilages ont été plus importantes au stade tardif que précoce. La mastication ingestive a réduit fortement la proportion de grosses particules (> 2 mm) (LP2) par rapport à la comminution totale. Cette diminution a été plus importante avec l'ensilage grossièrement haché qu'avec l'ensilage finement haché, respectivement de 73 à 38 % vs. de 58 à 37 %. Parallèlement, la durée unitaire d'ingestion par gramme de fourrage ingéré n'a pas varié significativement avec les deux ensilages (21.3 vs. 19.8 min·kg -1 MSI). La mastication était donc plus efficace pour l'ensilage haché grossière-ment.

Effects of ensiling maize and sample conditioning on in situ rumen degradation of dry matter, starch and fibre

“…The FG conditioning simulated soaked chewed particles during ingestion (Fernandez and Michalet-Doreau, 2002) but failed to take into account the essential chewing during rumination that reduces particle size to facilitate aNDF degradability by microbial enzymes (Beauchemin and Yang, 2005). Contrary to D1 and D4, the coarse grinding of the FG conditioning is likely insufficient to make aNDF accessible to microbial enzymes, which would explain the lower aNDF degradation of FG samples.…”

Physically Effective Fiber: Method of Determination and Effects on Chewing, Ruminal Acidosis, and Digestion by Dairy Cows

“…In addition, long particles are reduced in size during ingestive mastication, thereby eliminating the effects of particle length. Fernandez and Michalet-Doreau (2002) reported that mean particle length markedly decreased after ingestive mastication, and the decrease was greater for coarsely chopped than for finely chopped CS. Fermentability of concentrate could be another factor influencing digestion.…”

Silage review: Silage feeding management: Silage characteristics and dairy cow feeding behavior

“…At the same time, DMI decreased by 3.3 kg/d, indicating that it took the cows longer to consume less DM of more coarsely chopped silage. Similarly, Fernandez and Michalet-Doreau (2002) compared corn silage chopped to either 4.2 or 12.0 mm theoretical length of cut and observed that time spent eating was reduced by 43 min/d for cows fed the finer chopped silage despite similar DMI. Fernandez et al (2004) compared the effects of 2 corn silage hybrids varying in NDF digestibility either when finely or coarsely chopped (5 vs. 13 mm theoretical length of cut, respectively).…”