Effects of nutritional strategies on rumen environment and performance in dairy cows

direct-fed microbial;sub-acute ruminal acidosis;Rumen environment

Luan, Shaoyu

关键词: direct-fed microbial;    sub-acute ruminal acidosis;    Rumen environment;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/79519/Luan_Shaoyu1234.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Sub-acute ruminal acidosis (SARA) is a common condition affecting dairy cows and has up to 26% incidence in commercial dairy farms (Garrett et al., 1999; Kleen et al., 2003). Its association with DMI depression, milk yield depression, reduced feed efficiency, rumenitis, diarrhea, laminitis, inflammation, liver abscesses, and high culling and death rates in dairy cattle had been extensively reported by previous authors (Nocek, 1997; Kleen et al., 2003; Stone, 2004; Alzahal et al., 2007; Enemark, 2008). The effects of SARA on urine, fecal pH, milk yield and milk composition, and starch digestibility were determined. Six Holstein cows (HOL), six rumen-cannulated Holstein cows (CAN), and six Jersey cows (JER) were used in a replicated 3 × 3 Latin square design balanced to measure carry-over effects. Periods (10 d) were divided into 4 stages (S): S1, baseline, d 1-3, ad libitum TMR; S2, restricted feeding, d 4, cows fed for 50% of S1 DMI; S3, challenge, d 5, treatments applied; S4, recovery, d 6-10, all cows fed ad libitum TMR. Treatments were CON, no top dress; MOD, 10% of S1 DMI as top dress (pelleted mixture of 50:50, wheat: barley); and HIG, 20% of S1 DMI as top dress. Rumen pH and urine pH were recorded at -2 to 22 h relative to feeding on S3. Milk yield was recorded and DMI measured daily. Milk samples were obtained on d 2, 4, 5, and 8 for composition analysis. Fecal samples were obtained on d 1 afternoon (3 PM), d 4 morning (7 AM), afternoon (3 PM), night (11 PM), and the next morning before feeding (6 AM) for determination of fecal pH and starch digestibility. No treatment carry-over effect was observed for any measured variable. Mean rumen pH was depressed to 6.24 and 6.35 for cows in HIG and MOD respectively, which were lower than the 6.45 for cows in CON treatment. However, the area under curve was not different among treatments in rumen pH. Mean urine pH for HOL cows was lower on HIG (8.46) compared with 8.54 and 8.51 for CON and MOD, respectively. Mean urine pH of Jersey cows did not differ among treatments. Fecal pH was not different among treatments either for JER and HOL cows. However, fecal pH was lower 15 and 23 h after feeding in HOL cows when compared with other time points. Fecal pH was lower at 7, 15, and 23 h after feeding in JER cows than other time points. Milk yield and composition were not different among treatments. Milk urea nitrogen was elevated in S2 and S3 on all treatments for both HOL and JER cows. No treatment effects were found for fecal pH and starch digestibility. During S3, fecal pH was depressed from 7 to 23 h and 15 to 24 h post feeding for JER and HOL cows. Rumen pH can be predicted by urine pH within 2 h after feeding. Fecal pH may be used as a tool to predict rumen pH depression as early as 7 and 15 h after feeding for JER and HOL cows respectively. One alternative to modulate rumen environment is the utilization of direct-fed microbials (DFM) that has become common in the dairy industry, but questions regarding their value and mode of action remain prevalent. The objective of this study was to evaluate the effects of a DFM (Bacillus pumilus 8G-134) on pre-partum performance and prevalence of health disorders in early lactation. Thirty-nine multiparous Holstein cows were fed a TMR according to NRC (2001) recommendations and assigned to 2 treatments in a completely randomized block design. Cows in the direct-fed microbial treatment (DFMt, n = 21) received 5.0 x 109 cfu of B. pumilus in 28 g of media, whereas, cows in the control treatment (CON, n = 22) received 28 g of media. Treatments were top-dressed on the TMR daily. Treatments were applied from 21 d before expected calving date to 21 d after calving. Blood samples were analyzed for beta-hydroxybutyrate at d 5 and 14 after calving. Cows that had blood beta-hydroxybutyrate concentrations higher than 1.2 mmol/L were classified as experiencing sub-clinical ketosis. Treatment DFM tended to have lower haptoglobin concentration than DFMt cows on d 14. Treatment DFM had higher IgA concentration than CON cows on the first week after calving. Other health disorders recorded were retained placenta, displaced abomasum, clinical ketosis, and pneumonia. Fecal scores were recorded daily. Statistical analysis was performed using the MIXED and FREQ procedures of SAS. The DMI, BW, and BCS were not different between treatments through experiment. Cows fed DFMt had higher milk yield, fat corrected milk, energy correct milk, fat production and protein production on the second week of lactation, however there was no differences between treatments on milk yield and any milk components. Cows fed DFMt tended to have higher feed efficiency than cows fed CON. Cows fed DFMt tended to have less incidence of sub-clinical ketosis at d 5 but not at d 14 when compared to cows receiving CON. There were no treatment effects on the incidence of displaced abomasum, clinical ketosis, or pneumonia. Although occurrence of retained placenta was low, cows fed CON tended to have higher incidence of retained placenta than cows fed DFMt. Cows that received DFMt tended to have higher fecal score than CON. In conclusion, cows receiving DFMt tended to have decreased incidence of sub-clinical ketosis than cows receiving CON, potentially by reducing negative-energy balance after calving. Cows receiving DFMt tended to have higher feed efficiency than CON. Dry matter intake, BW, BCS were not affected by DFM supplementation. Cows receiving DFMt tended to have firmer fecal and potential better immunity than CON cows.