Influence of different sources of zinc and protein supplementation on digestion and rumen fermentation parameters in sheep consuming low-quality hay.

ARELOVICH, HUGO MARIO; AMELA, MARÍA INÉS; MARTÍNEZ, MARCELA FERNANDA; BRAVO, RODRIGO DAMIÁN; TORREA, MARÍA BEATRÍZ

JOURNAL OF SMALL RUMINANT RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 121 p. 175 - 182

0921-4488

tThis experiment studied the effect of ZnCl2or ZnSO4included into a protein supplementon dry matter intake (DMI), DM digestibility (DMD) and rumen fermentation parameters insheep consuming low-quality native pasture hay (NPH) as a basal diet. Four ruminally fis-tulated Corriedale weathers (31 ± 4 kg BW) were randomly assigned to a 4 × 4 latin squaredesign, and received NPH ad libitum in the following treatments: (1) Control (CON) mineralmix only, (2) protein supplement (PROT), (3) PROT + ZnCl2(CZProt) and (4) PROT + ZnSO4(SZProt). All supplements were fed at the rate of 150 g animal d−1. The Zn concentration inCZProt and SZProt was 460 ppm for a total intake of 100 ppm daily as a proportion of totaldiet. The NPH contained 5.3 and 77.4 of CP and NDF as % of DM respectively. Protein sup-plements were isonitrogenous (30% CP) with barley grain, wheat middlings and sunflowermeal as main components. Mean NPH intake and total DMI were not affected by proteinsupplementation or Zn addition to the diet. DM digestibility as well as DDMI (digestibleDMI) increased 31 and 37% respectively for SZProt compared to CON (P < 0.05). Samp-ling hour affected most rumen variables with the exception of butyric and total volatilefatty acids (VFA; P < 0.05). A treatment by sampling hour interaction (P < 0.05) was onlyfound for ruminal ammonia-N (NH3-N) concentration. At time intervals of 2, 4, 8 and 12 h,[NH3-N] was much lower in CON than in protein supplemental treatments (P < 0.05). Atrend was observed for increased NH3-N concentration in SZProt (39.76 mg dL−1) vs. CZProt(29.25 mg dL−1) at 4 h (P = 0.0897). The rumen pH was not affected by treatments; the lowestvalues found 12 h after feeding were 6.2. Zinc, particularly from SZProt, seems to modulate[NH3-N] by sustaining higher concentrations during the 24 h period. A clear effect on majorVFA was not observed. The inclusion of 100 ppm of Zn, and source could differentially affectanimal response to protein supplementation and utilization of low quality roughages byaffecting some rumen fermentation patterns.