The aim of this study was to check the accuracy of laboratory methods to predict the apparent protein digestibility (CPd, %) and digestible protein content (DP, g/kgDM) of dog foods, avoiding the use of experimental animals in digestion trials. Twenty-eight commercial dry extruded dog foods were tested by three different methodologies: an adaptation of the in vitro incubation method described by Hervera et al. (J Anim Physiol Anim Nutr 2007, 91: 205) for estimation of digestible energy of commercial dog foods, a modification of the pH drop methodology proposed by Hsu et al. (J Food Sci 1977, 42: 1269) for protein evaluation of human foods and the Near Infra Red Spectroscopy (NIRS) technology. All the methods assessed revealed very good, similar accuracy in the prediction of DP content either using the in vitro method (r = 0.99; RSD = 6.76; CV = 2.31%), the pH drop method (r = 0.99; RSD = 6.94; CV = 3.02%) or the NIRS (R2 = 0.96; SECV = 10.50) method, although the in vitro digestion method showed the highest accuracy approach of in vivo crude protein apparent digestibility: CPd in vitro (r = 0.81; RSD = 2.01; CV = 2.41%); CPd pH-drop (r = 0.78; RSD = 2.48; CV = 2.98%) and NIRS (r(2)cv = 0.53; SECV = 2.37).

No abstract

No abstract

No abstract

The effect of storage method and length of the fermentation period were evaluated to determine fermentation characteristics, aerobic stability, and forage intake of native tropical grasses ensiled in round bales. Bales were stored under shade or under direct sunlight and sampled after seven periods of ensiling (0, 1, 4, 11, 25, 53, and 111 d). For the aerobic stability and nutritive value studies, three bales were opened from each storage method after 53 and 111 d, exposed to air, and fed to heifers for voluntary consumption. The storage method did not affect fermentation characteristics, however, during aerobic exposure, silage storage under shade resulted in less deterioration as evidenced by lower pH, temperature, and microbial populations. Also, the shorter length of fermentation (53 d) resulted in lower pH and temperature and enhanced aerobic stability. The combination of silage storage under shade and short length of fermentation resulted in the most stable silages and did not improve the nutritive value of native tropical grasses ensiled in large round bales as evidenced by similar forage intake.