An investigation of carbohydrate and protein degradation ratios, nitrogen to energy synchronization and hourly effective rumen digestion of barley: effect of variety and growth year

Abstract

The objective of this study was to investigate rumen available soluble, insoluble and total protein (CP), estimated structural (SC) and non-structural carbohydrate (starch: ST), degradation characteristic ratios and hourly effective degradation of six barley varieties during three consecutive growth years (2003, 2004, 2005). The magnitude of the differences was determined between the varieties and growth years. Measured degradation kinetics included soluble fraction (S), undegradable fraction (U), lag time (T(0)) and rate of degradation (K(d)) of the insoluble but degradable fraction (D). Rumen available soluble, insoluble, and total N, SC and ST and the rumen degradation characteristic ratios were determined using the Tamminga rumen degradation ratio system. Characteristics of the hourly effective degradation between N and carbohydrate (CHO) among the six barley varieties for 3 years were also studied. The degradation ratios included were total rumen available N and carbohydrate ratio (FN/FCHO), rumen available soluble N and carbohydrate ratio (SN/SCHO), and rumen available insoluble N and carbohydrate ratio (EN/ECHO). Results show that both the barley variety and growth year had a significant effect on degradation kinetics (S, D, U, T(0) and/or K(d)). Differences in the ratio of FN/FCHO among varieties ranged from 16.6 to 19.0 g/kg (p < 0.01). There was no difference in SN/SCHO (p > 0.05) with an average of 4.9 g/kg. The difference in the EN/ECHO ratio tended to be significant among the varieties (p = 0.069) ranging from 18.4 to 21.3 g/kg. Differences in the hourly effective degradation between N and CHO were relatively small at shorter incubation times (2-4 h) However, as the length of rumen incubation increased (12-24 h), much larger differences in the rate of effective hourly degradation were observed. In conclusion, both barley variety and growth year had significant effects on rumen degradation kinetics. The mean FN/FCHO ratio of 17.2 (16.6-19.0) was observed for the six barley varieties in this experiment. All barley varieties exhibited a less optimal rumen fermentation ratio (17.2 < optimum: FN/FCHO = 25 to 33 g N per kg CHO). The large differences in the degradation kinetics, characteristics ratios and hourly effective degradation among barley varieties and growth years may help to explain some of the large variations that are seen in cattle performance.

Protein Structures among Bio-Ethanol Co-Products and Its Relationships with Ruminal and Intestinal Availability of Protein in Dairy Cattle

“…The cows had free access to water and were fed 15 kg DM/day total mixed ration twice daily in equal portions at 8.00 a.m. and 4.00 p.m. The total mixed ration consisted in %DM of 55% barley silage, 12.5% alfalfa hay, 5% dehydrated alfalfa and 27.5% concentrates as described in Yu et al [23]. …”

Nutrient profile and availability of co‐products from bioethanol processing

“…The cows were individually housed in pens at the experimental farm of the University of Saskatchewan (Saskatoon, SK, Canada) and cared for according to the Canadian Council on Animal Care guidelines (CCAC 1993). The animals had free access to water and were fed twice daily at 08:00 and 16:00 h with 14 kg/day of a totally mixed ration as described by Yu et al. (2009).…”

Effects of canola meal pellet conditioning temperature and time on ruminal and intestinal digestion, hourly effective degradation ratio, and potential nitrogen to energy synchronization in dairy cows

“…The hourly ED-N/ ED-CHO ratio increased rapidly from 0 to 2 h for all treatments, demonstrating a rapid increase in N concentration in the rumen during the first 2 h of canola feeding. Yu et al (2009) andNuez-Ortín andYu (2010) indicated that the difference in hourly degradation of N was a main reason to change the hourly ED-N/ED-CHO ratio. Thus, the difference between unprocessed mash and pelleted samples in hourly ED-N/ED-CHO was likely due to the increased CP degradation caused by pelleting.…”