Determination of the ruminal escape value and duodenal amino acid flow of rapeseed meal

Effect of processing method on in sacco ruminal degradability of organic matter and nitrogen from canola seeds and in vitro intestinal nitrogen digestion of the in sacco residue

A novel crop on the Southern Plains of the United States is canola (Brassica napus L.), of which annual production has nearly doubled in the last 5 years. Although production has not exceeded the demand for oil, the question has arisen as to its supplemental value for cattle grazing the rangeland adjacent to production areas. In an experiment, six seed processing methods were evaluated by in sacco digestion of organic matter and nitrogen and in vitro intestinal in sacco residue: (1) whole seeds with no processing; (2) seed coats scarified in a pneumatic seed scarifier; (3) ground in a four-knife mill; (4) unprocessed seed rolled to 0.5 mm thick; (5) seeds roasted then rolled to 0.5 mm thick; and (6) steamed then rolled to 0.5 mm thick. Processing methods were compared with a solvent-extract canola seed meal. All processing methods increased in sacco organic matter and nitrogen digestion in the rumen with ground method being the greatest (P < 0.05). These results showed that the ground method produced the most (P < 0.05) ruminally degraded nitrogen/kilogram of organic matter digested in the rumen (67 g) of all methods evaluated. Further, extent of in vitro nitrogen digestion (intestinal) from in sacco residue was reduced by increases in ruminal digestion. Processing methods that broke the seeds increased (P < 0.05) the total extent of nitrogen digestion over whole and scarified treatments. The most limiting nutrient to augment energy intake and digestion in cattle grazing native pastures is ruminally degraded nitrogen and it seems that the most appropriate processing method is grinding to use whole canola seeds as a supplement. Other processing methods evaluated either increased processing cost or increased the ruminally undegraded nitrogen value.

Effects of canola seed supplementation on intake, digestion, duodenal protein supply, and microbial efficiency in steers fed forage-based diets1

Fourteen Holstein steers (446 +/- 4.4 kg of initial BW) with ruminal, duodenal, and ileal cannulas were used in a completely randomized design to evaluate effects of whole or ground canola seed (23.3% CP and 39.6% ether extract; DM basis) on intake, digestion, duodenal protein supply, and microbial efficiency in steers fed low-quality hay. Our hypothesis was that processing would be necessary to optimize canola use in diets based on low-quality forage. The basal diet consisted of ad libitum access to switchgrass hay (5.8% CP; DM basis) offered at 0700 daily. Treatments consisted of hay only (control), hay plus whole canola (8% of dietary DM), or hay plus ground canola (8% of dietary DM). Supplemental canola was provided based on the hay intake of the previous day. Steers were adapted to diets for 14 d followed by a 7-d collection period. Total DMI, OM intake, and OM digestibility were not affected (P > or = 0.31) by treatment. Similarly, no differences (P > or = 0.62) were observed for NDF or ADF total tract digestion. Bacterial OM at the duodenum increased (P = 0.01) with canola-containing diets compared with the control diet and increased (P = 0.08) in steers consuming ground canola compared with whole canola. Apparent and true ruminal CP digestibilities were increased (P = 0.01) with canola supplementation compared with the control diet. Canola supplementation decreased ruminal pH (P = 0.03) compared with the control diet. The molar proportion of acetate in the rumen tended (P = 0.10) to decrease with canola supplementation. The molar proportion of acetate in ruminal fluid decreased (P = 0.01), and the proportion of propionate increased (P = 0.01), with ground canola compared with whole canola. In situ disappearance rate of hay DM, NDF, and ADF were not altered by treatment (P > or = 0.32). In situ disappearance rate of canola DM, NDF, and ADF increased (P = 0.01) for ground canola compared with whole canola. Similarly, ground canola had greater (P = 0.01) soluble CP fraction and CP disappearance rate compared with whole canola. No treatment effects were observed for ruminal fill, fluid dilution rate, or microbial efficiency (P > or = 0.60). The results suggest that canola processing enhanced in situ degradation but had minimal effects on ruminal or total tract digestibility in low-quality, forage-based diets.

Level of supplemental protein does not influence the ruminally undegradable protein value

Two experiments were conducted to determine whether elevating the percentage of ruminally undegradable protein (RUP) in the diet would influence the RUP value of the protein feedstuff. A single-effluent, continuous-culture study was designed to test the effect of RUP inclusion rate in the diet on ruminal degradability of the protein. Treatments consisted (DM basis) of a control diet with no supplemental protein, control + 2.5% bloodmeal (BM-L), control + 5% bloodmeal (BM-H), control + 4.45% soybean meal (SBM-L), and control + 8.89% soybean meal (SBM-H). Proteolytic activity and total VFA concentration were not affected (P = 0.73 and P = 0.13) by treatment. Within protein source, dietary RUP value was not affected (P = 0.94) by level of inclusion. When corrected for control diet RUP flow, the RUP value of the blood meal (BM) protein was higher (P = 0.01) than soybean meal (SBM); however, level of supplementation did not affect (P = 0.07) the RUP value of BM or SBM. In Exp. 2, 32 British x Continental crossbred steers (276 +/- 26.3 kg) were fed for 72 d to examine the effects of balancing the AA:energy ratio, using BM as a RUP source, on ADG, G:F, and lean tissue deposition. Diets were formulated to provide increasing levels of arginine, while ruminally degradable protein and energy were held constant. Four dietary treatments provided 0.5, 1, 1.5, and 2x the required amount of arginine, whereas the control diet had no BM included. Daily DMI averaged 7.6 kg/steer and did not differ (P = 0.71) among treatments. Steers gained an average of 1.9 kg/d and average G:F was 0.260, with no differences (P = 0.60 and P = 0.97, respectively) among treatments. There was no difference (P = 0.48) in the change in 12th-rib fat depth during the study; however, change in LM area was affected quadratically as the level of BM increased in the diet, with the greatest increase in LM area occurring in steers fed the 1x and 1.5x required arginine treatments. Balancing the AA:energy ratio did not affect G:F, DMI, or ADG; however, it increased deposition of lean in the LM quadratically. Level of dietary inclusion of BM as an RUP source does not affect its RUP value or efficacy of providing postruminal AA in growing steers.

Canola and sunflower meal in beef cattle diets

It is apparent from the limited research that sunflower meal is a biologically and economically useful protein source for growing and finishing cattle. Similarly, beef cows can be provided supplemental protein effectively with sunflower meal. Sunflower meal may be especially useful in diets where degradable protein is required, such as lower quality forage or high corn finishing rations. The increased bulk of this relatively high fiber meal may affect logistics, but ruminants are positioned to be more tolerant of high fiber levels than other species. Additional research is warranted to evaluate practical and economic aspects of using sunflower meal in beef cattle diets.

Rumen dry matter and crude protein degradability of extracted or untreated oilseeds and Leucaena leucocephala leaves

A study was undertaken to determine the rumen DM and CP degradability characteristics of soyabean, canola seed, peanut, palm kernel and Leucaena leucocephala leaves. The oilseeds were either treated with n-hexane to extract the fat or left untreated. Nylon bags were incubated in each of four rumen cannulated sheep for 0, 2, 4, 6, 12, 24 and 48 h. Animals were fed on a diet consisting of meadow hay (ad libitum) and 150 g of concentrate twice daily. Fat extraction caused a decrease (P < or = 0.05) in DM disappearance of soyabean at 0, 2, 4, 6 and 12 h and of peanuts at all incubation times. CP disappearance from peanuts was reduced (P < or = 0.05) as a result of fat extraction at 0, 2, 4, 6 and 12 h. Fat extraction of canola seed increased CP disappearance at 0, 2, 4, 6 and 24 h (P < or = 0.05). However, in the case of defatted canola seed, an increase in DM disappearance (P < or = 0.05) was observed in the first 4 incubation times and a decrease (P < or = 0.05) in the later times. Fat extraction increased (P < or = 0.05) DM disappearance of palm kernel at 0 and 48 h, but reduced it at 4, 6 and 24 h. CP disappearance of palm kernel was improved by treatment (P < or = 0.05) at 0, 4, 24 and 48 h and decreased at 12 h. In the case of palm kernel the largest differences in DM and CP disappearance occurred between the 24 and 48 h incubation times. Degradability characteristics for DM and CP of full-fat soyabean, canola seed and peanut were comparable to those of the full fat samples. Effective DM degradability of soyabean, canola seed and peanuts was 72.2 and 71.9; 74.1 and 66.8; and 85.9 and 70.8 for full fat and extracted feeds, respectively. Effective CP degradability was similar in all oilseeds with the exception of the extracted canola seed. Therefore, the incorporation of full-fat soyabean, canola seed and peanut into ruminant rations can be considered as a means of increasing the energy balance. Both palm kernel DM and CP degradabilities were characterized by slow rates of degradation by negative values "b". This suggests the predominance of microbial colonization over disappearance during incubation. DM and CP disappearance of Leucaena leucocephala leaves originating from Cuba were lower than those from Nigeria. Degradability characteristics for CP and DM of Cuban leucaena leaves showed that the linear model resulted in a better fit than the exponential one.