Effects of corn-based diet starch content and corn particle size on lactation performance, digestibility, and bacterial protein flow in dairy cows

Abstract

An experiment was conducted to determine the effects of dietary starch content in corn-based diets and corn particle size on lactation performance, nutrient digestibility, and bacterial protein flow in dairy cows using the omasal and reticular sampling technique. Eight ruminally cannulated lactating multiparous Holstein cows were used in a replicated 4×4 Latin square design with a 2×2 factorial arrangement of treatments. Treatments were fine (FG; mean particle size=552µm) and coarse (CG; 1,270µm) ground dry shelled corn in normal- (NS) and reduced- (RS) starch diets fed as total mixed rations. The NS and RS rations contained 27 and 18% starch (dry matter basis), respectively, and were formulated by partially replacing corn with soy hull pellets. Mean dry matter intake was unaffected by treatment (23.2kg/d). Cows fed NS diets produced 1.9kg/d more milk and 0.06kg/d more milk protein compared with cows fed RS diets. Cows fed NSFG and RSCG diets produced more fat-corrected milk than did cows fed NSCG and RSFG diets. Milk urea concentration was decreased for cows fed NS diets (12.4mg/dL) compared with RS diets (13.5mg/dL). Ruminal digestibility of neutral detergent fiber (NDF; % of NDF intake) determined by the omasal sampling technique was increased in cows fed RS diets compared with NS diets (43.4 vs. 34.9%), and total-tract digestibility of NDF (% of NDF intake) was increased in cows fed RS diets compared with those fed NS diets (50.1 vs. 43.1%). Ruminal digestibility of starch (% of starch intake) determined by the omasal sampling technique was greater in cows fed NS diets compared with those fed RS diets (85.6 vs. 81.6%). Total-tract starch digestion was increased in cows fed RS diets compared with those fed NS diets (96.9 vs. 94.6%) and in cows fed FG diets compared with those fed CG diets (98.0 vs. 93.5%). Bacterial protein flow was unaffected by treatment. The omasal and reticular sampling techniques resulted in similar treatment effects for nutrient flow and digestibility, although nutrient flow was lower and nutrient digestibility was greater in cows when sampled by the omasal technique compared with the reticular technique. Cows fed FG diets had greater ruminal propionate, lower acetate:propionate ratio, and lower pH. Feeding NS diets increased milk and protein yields and feeding finely ground corn increased ruminal propionate concentration.

Production, milk and plasma fatty acid profile, and nutrient utilization in Jersey cows fed flaxseed oil and corn grain with different particle size

“…coming from starch in cows fed the normal starch diet was independent of BW, BCS, and milk yield, which did not differ significantly across treatments in the study of Fredin et al (2015). However, a trend for an interaction between starch level and corn PS was observed for milk fat yield, thereby suggesting that additional energy from increased starch digestibility may have been used to produce milk fat in their experiment (Fredin et al, 2015). In the meta-analysis of Ferraretto et al (2013), the apparent total-tract digestibilities of DM, OM, and starch decreased as dry corn grain PS increased without an effect on NDF digestibility, which corroborate our results.…”

“…These discrepancies in microbial protein synthesis measured directly using purines as the bacterial marker (Ueda et al, 2003;Gonthier et al, 2004) or estimated indirectly via urinary excretion of PD (present study) may be associated with differences in the composition and proportion of dietary ingredients and whether flaxseed was offered as oil or grain. coming from starch in cows fed the normal starch diet was independent of BW, BCS, and milk yield, which did not differ significantly across treatments in the study of Fredin et al (2015). However, a trend for an interaction between starch level and corn PS was observed for milk fat yield, thereby suggesting that additional energy from increased starch digestibility may have been used to produce milk fat in their experiment (Fredin et al, 2015).…”

“…Knowlton et al (1998) reported no difference in the duodenal flow of bacterial N in lactating dairy cows fed GC or rolled corn with mean PS of 618 and 1,725 μm, respectively. Similarly, the omasal flow of bacterial NAN was not affected by corn grain PS (finely vs. coarsely ground) with feeding normal or reduced starch diets to lactating dairy cows (Fredin et al, 2015). Even though is conceivable that more fermentable energy would be available for microbial use in the rumen when feeding finely rather than coarsely ground corn, urinary excretion of PD (current study) or microbial protein synthesis measured directly using purines (Knowlton et al, 1998) or 15 N (Fredin et al, 2015) as bacterial markers were not affected, possibly due to tradeoffs among ruminal pH, fiber digestibility, and microbiota growth.…”

Production and nitrogen utilization in lactating dairy cows fed ground field peas with or without ruminally protected lysine and methionine

“…Furthermore, despite the significant increase in starch intake (0.37 kg/d; Table 3) in cows fed FPAA versus FP, the difference between treatments was likely too small to influence the concentration of true protein in milk or Met in plasma. For instance, a larger difference in starch intake (2.1 kg/d) between normal-(mean = 26.5%) and reduced-starch (mean = 18.2%) diets did not affect DMI, concentration of milk true protein, and omasal flow of bacterial NAN (Fredin et al, 2015). Milk true protein yield did not change and averaged 1.23 kg/d when feeding FPAA versus FP (Table 3).…”

Düşük Nişastalı Rasyonlarla Beslenen Geçiş Dönemindeki İneklerde Amilaz Enziminin Etkisi: 2. Toplam Sindirilebilirlik ve Kan Üre Azotu

“…Starch is fermented and increases propionate production in the rumen [2] , and unfermented starch that escapes ruminal fermentation provides glucose that is absorbed or metabolized to lactate in the small intestine [3] . Starch level [4,5] and starch content [6,7] in ration was assessed in terms of performance in dairy cows.…”