Juice-Extracted Grass Pellets and Sodium Bicarbonate for Cows Fed Timothy Silage of Two Chop Lengths

¹ Département des Sciences Animales, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Sainte-Foy, QC, Canada G1K 7P4
² Service de la Zootechnie, Direction de la Recherche et du Développement, Ministère de l'Agriculture, des Pêcheries et de l'Alimentation du Québec, Deschambault, QC, Canada G0A 1S0

Eighteen multiparous Holstein cows in midlactation were used in a switchback design trial to evaluate the effect of chop length (3 or 30 mm) of timothy grass silage, containing less than 30% ADF and treated with formic acid, on DMI and cow performance. Within chop length, the addition of NaHCO₃ (2% of DMI) or the replacement of 30% of silage DM with juice-extracted grass pellets was also evaluated. Cows were fed a TMR composed of 90% silage and 10% concentrate. Silage preservation characteristics were not different between chop lengths. The DMI and apparent digestibility were similar among treatments. Yields of 4% FCM (24.9 vs. 22.7 kg/d), fat (1.03 vs. .93 kg/d), and protein (.83 vs. .77 kg/d) were higher with the short chopped silage. Milk protein, milk NPN content, and serum urea were higher for cows fed long chopped silage. Yields of milk and milk constituents were not affected by the addition of juice-extracted grass pellets or NaHCO₃. Fat percentage and fatty acid composition of milk remained unchanged by treatments. Reduction of particle size, from 30 to 3 mm, of timothy grass, treated with formic acid at harvest and using compaction at ensiling in bag silos, did not affect silage conservation characteristics but did improve milk, fat, and protein yields when cows were fed high silage diets.

Key Words: chop length • timothy silage • sodium bicarbonate • milk

Submitted on August 22, 1994
Accepted on June 16, 1995