Influence of barley grain particle size and treatment with citric acid on digestibility, ruminal fermentation and microbial protein synthesis in Holstein calves

Abstract

Chemical and physical treatments of barley grain increase ruminally resistant starch and can improve the rumen fermentation pattern. The objective of the present study was to evaluate the effects of chemical (addition of citric acid, CA) and physical (grinding to two different particle sizes, PS) treatment of barley grain on performance, rumen fermentation, microbial protein yield in the rumen and selected blood metabolites in growing calves. In all, 28 male Holstein calves (172 ± 5.1 kg initial BW) were used in a complete randomised design with a factorial arrangement of 2 barley grain particle sizes × 2 levels of citric acid. The diets were as follows: (i) small PS (average 1200 µm) barley grain soaked in water (no CA addition); (ii) small PS barley grain soaked in a CA solution (adding 20 g CA/kg barley); (iii) large PS (average 2400 µm) barley grain soaked in water (no citric acid addition) and (iv) large PS barley grain soaked in a citric acid solution (adding 20 g CA/kg barley). Barley grain was then incorporated at 35% in a total mixed ration and fed to the calves for 11 weeks. Feeding small PS barley decreased feed intake ( P = 0.02) and average daily weight gain ( P = 0.01). The addition of CA to barley grain did not affect intake but increased weight gain ( P < 0.01) and improved feed to gain ratio ( P = 0.03). Digestibility of organic matter and NDF tended ( P < 0.10) to increase, whereas faecal scoring was improved ( P = 0.03) and the presence of undigested grain particles in faeces was reduced ( P < 0.01) with CA-treated barley grain. Glucose and urea concentrations were increased (P < 0.01) in the blood of calves fed the CA-treated barley grain. Ruminal pH tended ( P = 0.08) to be decreased with more finely ground barley and was increased when barley grain was treated with CA. Total volatile fatty acid concentrations in the rumen did not differ among treatments ( P > 0.05). However, the molar proportion of propionate was increased ( P = 0.03) when barley was more finely ground, and that of acetate was increased ( P = 0.04) when CA was added to barley grain. The ruminal concentration of ammonia nitrogen was increased ( P < 0.01) and microbial nitrogen synthesis in the rumen tended to decrease by adding CA to barley. Treating barley grain with citric acid increased fibre digestibility of total mixed rations, attenuated the decrease in ruminal pH, and improved weight gain and feed efficiency in male Holstein growing calves fed a high-cereal diet (550 g cereal grain/kg diet).

Effects of linseed oil and rumen undegradable protein:rumen degradable protein ratio on performance of Holstein dairy calves

“…The other probable mechanism may be related to increased blood insulin concentration in response to supplemented some individual FA which was reported previously in beef cows fed with polyunsaturated plant FA (44) . Furthermore, sparing effect of FA for amino acid and glucose could increase these metabolite concentrations in the blood (9) that consequently both glucose (45) and amino acids (46) had potential to increase blood insulin concentration. The young calves are highly sensitive to insulin similar to non-ruminants (47) , and long-term effect of insulin concentration in dairy calves on future insulin sensitivity status may be a controversial issue.…”

Grain grinding size of cereals in complete pelleted diets for growing lambs: Effects on ruminal microbiota and fermentation

“…A possible approach to reduce the fermentation rate of starch in the rumen would be to modify the cereal particle size (grinding size) included within the pellet, as it is well known that lambs can use the whole grain cereal efficiently (Ørskov and Fraser, 1975). Feed intake, rumen ecosystem and fermentation parameters can be affected by cereal particle size (Pérez-Torres et al, 2011;Gimeno et al, 2015a;Kazemi-Bonchenari et al, 2017), but to the authors' knowledge there are no studies integrating all this information in weaned lambs intensively fattened during short periods of time (less than 50 days) with CPD. Changing grinding size of grain may cause changes in the composition of ruminal microbiota, affecting the rate of fermentation and the formation of end-products, and then the composition of ruminal contents and digesta reaching the abomasum.…”

Effects of a Grain Source (Corn Versus Barley) and Starter Protein Content on Performance, Ruminal Fermentation, and Blood Metabolites in Holstein Dairy Calves

“…Khan et al [ 3 ] reported that lower ruminal pH in the calves fed on BG depressed intake. Different particle size, [ 11 ] as well as starch availability rate [ 10 ] could influence ruminal pH. However, similar ruminal pH across experimental diets were observed in the current study, which was partly because GMPS was similar among experimental diets ( Table 1 ).…”

“…A linear decrease in ruminal NH 3 -N concentration in dairy cows was reported as a result of an increasing proportion of BG in the diet [ 9 ]. This may be related to the BG starch structure which is rapidly degradable and easier accessible for ruminal microbes [ 9 , 10 ]. DePeters and Fergusen [ 33 ] reported that BUN could be used as an indicator of ruminal N captures, as this value is positively associated with ruminal NH 3 -N concentration.…”

“…This can be critical for dairy calves when they are fed with high-starch grains as they are more susceptible to ruminal pH drop than mature ruminants [ 8 ]. However, high levels of BG are commonly incorporated in rations of dairy cows [ 9 ], fattening bulls [ 10 ], and dairy calves [ 3 , 11 ]. Optimum dietary particle size [ 12 ], adequate level of forage in the diet [ 13 , 14 ], and proper fermentation rate of starch [ 15 ] are major factors influencing the feeding efficiency of high-starch grains in dairy calves.…”