Ruminal degradability of crude protein from different treated soybean meals in lactating cows

Abstract

Ruminal crude protein (CP) degradability of four commercially available soybean meal (SBM) types--untoasted (U), toasted (T), heat-treated (H) and formaldehyde-treated (F)--was studied by the use of in sacco and in vivo techniques with lactating German Friesian cows cannulated in the rumen, duodenum and ileum. In two in sacco experiments three cows were fed a diet based either on grass hay plus ear-maize silage or on barley whole plant silage. Ruminal degradation rate of CP was estimated as percent nitrogen (N) disappearance from polyester bags incubated in the rumen for 2, 4, 6, 8, 12 and 24 h. Ruminal degradation rate of CP varied among the four SBM types as well as between the two basal diets. N disappearance from the bags after 12 h of incubation averaged 96, 67, 37, and 23% for the U, T, H, and F SBM types, respectively, in the cows fed the hay/ear-maize silage diet vs 99, 86, 58 and 41% for the four SBM types, respectively, in the cows fed the barley whole plant silage diet. In the in vivo experiment, four cows were fed diets based on meadow hay and ear-maize silage in a 4 x 4 Latin square design. The effect of SBM treatment on the flow rate of non-ammonia N (NAN) into the duodenum, and its relationship with the ruminal degradation rate of CP of the four SBM types, was studied. Formaldehyde treatment increased the amount of NAN entering the duodenum (P less than .05): 485 g cow-1 day-1 compared to 383, 418 and 428 g for U, T and H, respectively. Calculated ruminal CP degradabilities were 93, 75, 71 and 38% for SBM types U, T, H and F, respectively.

Effects of amount of intake and stage of forage maturity on urinary allantoin excretion and estimated microbial crude protein synthesis in the rumen of steers

“… †Organic matter apparently digested in the rumen; it was assumed that 60% of whole‐tract OM digestion occurred in the fore‐stomachs (Schröder et al., 1989, 1997; Südekum et al., 1992, 1994). …”

“…The quantity of OM apparently digested in the rumen (ADOMR, kg/day) was obtained by multiplying the intake of digestible OM by the factor 0.6, i.e., the proportion of whole‐tract OM digestion occurring in the rumen. This value was the mean derived from experiments with dairy cows fed on a total of 10 mixed rations in earlier studies (Schröder et al., 1989, 1997; Südekum et al., 1992, 1994). This value is only slightly lower than the factor 0.64 reported by Rohr et al.…”

Mejora del valor proteico para rumiantes de la harina de girasol mediante tratamientos combinados con ácidos (málico y fosfórico) y calor = Improvement of the protein value for ruminants of sunflower meal by combined treatments with acids (malic and orthophosphoric) and heat

“…El tratamiento con formaldehido ha sido el tratamiento químico más ampliamente empleado para proteger la degradabilidad ruminal de la proteína. Su eficacia para disminuir la degradabilidad ruminal se ha demostrado en diversos estudios, in vitro (Waltz y Stern 1989), in situ , Spears et al 1985, Ceresnáková et al1989) e in vivo (Schröder et al 1989).…”