Effect of particle size upon dry matter intake and ruminal pH in goats fed with alfalfa hay and sorghum silage

Abstract Text:

The aim of this work was to evaluate the effect of particle size on dry matter intake and ruminal pH in Alpine goats. The experiment was designed as a 4x4 latin square with 8 goats at the end of lactation. Treatments considered a 2x2 factorial arrangement; two forage particle lengths of alfalfa hay [short (1±0.03 cm) and long (4±0.05 cm)], combined with two different alfalfa hay and sorghum silage ratio (75:25 or 50:50). The forage:concentrate ratio was 60:40 for all rations. The particle size distribution of the diets was determined with the Penn State Particle Separator using the screen 2 and 3. Each period consisted of 11-d of adaptation stage and 3-d of experimental measurements. Subsequently, diets were exchanged during three periods. Offered food and orts were measured and recorded daily during the last 3-d of each period in order to calculate food intake. Ruminal fluid was collected on d-14 at 0700, 1100, 1500, 1900, 2300 and 0300 h and ruminal pH was immediately measured. According to our results, alfalfa hay particle size did not affect voluntary intake (Table 1), while silage can replace hay without affecting food intake or ruminal pH.

Table 1. Dry matter intake and ruminal pH affected by alfalfa hay particle size.

Diet	50:50		75:25
	Long	Short	Long	Short	SE	p- Value
DMI	1.39	1.44	1.45	1.53	0.38	NS
Ruminal pH	6.2	6.2	6.2	6.2	0.3	NS

Keywords: goat, particle size, dry matter intake, ruminal pH