Preparation Of Rumen-Protected Choline And Its Application In Holstein Dairy Cows

For the high-yielding dairy cows, choline synthesized by ruminal microflora or from dietary sources protected from the rumen degradation may not be sufficient to meet the requirement. Choline may need to be added.It is demonstrated that dietary choline is largely degraded in the rumen, and only a very limited amount of choline can escape from the rumen degradation. Therefore, it is necessary to develop nutritional strategies to protect choline from degradation by ruminal microflora, so that the rumen protected choline (RPC) can be available for milk production and metabolic needs. This study was conducted to develop the RPC and to evaluate it as feed additive in lactating dairy cows, and the following series of experiments were performed:Preparation of RPC (Expt 1); Stability of the RPC in air and in the rumen (Expt 2); Effects of RPC addition on milk production in lactating dairy cows (Expt 3); Effects of RPC addition on milk performance and plasma metabolic parameters in transition dairy cows (Expt 4); Effects of RPC and folic acid addition on milk performance and plasma metabolic parameters in transition dairy cows (Expt 5).In Expt 1, three trials were carried out to prepare the PRC and evaluate the protection effect. First trial (trial 1), was to investigsate the protection of choline from solubility by trundle pan coating method. According to an orthogonal design, evaluation was made for choline chloride with vegetable or silica supporter as the core materials and resins as the primary shell materials. Rate of insolubility tended to higher in choline chloride with silica supporter (17.4-19.2%) than that with vegetable supporter (6.5-7.4%), and increase with the increasing amounts of the resins. Trial 2 was conducted to study the protection of choline from solubility by pelleting. Similarly, evaluation was made for choline chloride with vegetable or silica supporter as the core materials but solid fats as the primary shell material according to an orthogonal design. The insolubility rates of choline chloride with vegetable or silica supporters ranged from 41.5-48.0% or 49.6-64.2% by once pelleting, and 35.8-42.9% or 43.3-58.9% by twice pelleting, respectively. Use of solid fat tended to increase the insolubility rate of choline chloride with vegetable supporter, but significantly reduced the insolubility rate of choline chloride with silica supporter. In trial 3, the protection of choline chloride with silica supporter by pelleting was studied. Solid fats as the primary shell material was selected in an orthogonal design. The insolubility rate of choline chloride with silica supporter ranged from 83.9 and 72.9% by once and twice pelleting, respectively. These results implied that compared to trundle pan coating method, pelleting can protect choline chloride from solubility more effectively; that choline chloride with silica supporter had higher effect of protection than the vegetable supporter; and the protection rate of choline by once pelleting was higher than twice for both two supporters.In Expt 2, the stability of the RPC in air and in the rumen was studied. In the first trial, comparison was made for the saturation moisture absorption rate of unprotected and pelleted choline chloride. The unprotected choline chloride absorbed more water in 10 hours than the pelleted (6 vs 2%), and both products reached their peak saturation moisture absorption rate during 90 hours (12 vs 4%)。The second trial was conducted to determine the release of the unprotected and pelleted choline chloride in artificial saliva at different incubation times. The unprotected choline chloride extensively released during less than 2 hours, but the release rate of pelleted choline chloride was only about 10% after 2 hour incubation, then increased to 35% at 24 hour incubation. In trial 3, the ruminal, post-ruminal and total tract degradation of pelleted choline chloride were evaluated using the in situ mobile bag technique and three-step in vitro enzyme procedure. The unprotected choline chloride was mostly degraded less than 2 hours both in rumen and post-rumen and more than 90% of choline chloride was degraded. Disappearance of choline chloride from the pelleted samples in the rumen was about 20% after 2 hours in both in situ bag and the three-step in vitro enzyme procedure, and then increased to 60% after 24 hours. The estimated rumen effective degradability of choline from the pelleted choline chloride was 35.0% at 24 hours. These results indicated that the pelleted choline, while protected from rumen degradation, can be effectively digested in the intestine and the estimated whole tract digestibility of choline from the pelleted samples was about 97.7%.Expt 3 was conducted to investigate the effects of RPC addition on milk performance and plasma metabolic parameters in lactating dairy cows. The effect of RPC addition on milk production and plasma metabolic parameters in transition cows was investigated in the first trial. Fourteen multiparous dairy cows were supplemented with 0 or 20 g/d of RPC from 7 d before expected calving to 21 d postpartum. Feeding of RPC tended to produce more milk and 4% fat-corrected milk (FCM) than those in the control group, while DM intake was not affected. There were no significant differences in percentages of milk fat and lactose both two groups. Treatment resulted in a slight increase in milk protein over the control. Plasma concentration of glucose and non-esterifed fatty acid (NEFA) for RPC-supplemented cows tended to increase and be lower than the control, while plasma concentrations of aspartate aminotransferase (AST), alanine amiotransferase (ALT), very low density lipoprotein (VLDL), triglycerides and cholesterol were not significantly different between the two groups. Trial 2 was purposed to to study the effect of RPC addition on milk production and milk composition in lactating dairy cows at peak. Forty-eight dairy cows were equally divided into two groups according to the parity, milk yield and milk in day. The cows in treatment group were supplement with 60 g RPC per day per cow. Cows consumed RPC tended to produce more milk than the control. There was no significant difference on milk composition percentage, although there was a tendency for increased milk fat percentage by RPC addition. In trial 3, the effect was studied of RPC addition on milk production and milk composition in dairy cows at mid-lactation. Forty-four dairy cows were equally divided into two groups according to the parity, milk yield and day in milk. The cows in treatment group were supplement with 25 g RPC per day per cow and conducted in two dairy farms, involving 22 lactating cows in each. The animals added with RPC tended to produce more milk than the control in both farms. No significant difference on milk protein and fat was observed in both farms. These results showed that addition of RPC is helpful to lactating dairy cows, and RPC could be more beneficial for transition dairy cows.Expt 4 was conducted to study the effect of RPC addition on milk performance and blood metabolic parameters in transition dairy cows. Thirty-six cows (24 multiparous and 12 primiparous) were equally divided into four groups by date of calving and parity. The cows were added with 0,30,60 or 90 g/d RPC from 15 d before expected calving to 15 d post partum. DM intake by cows was similar among the groups. Feeding of RPC tended to increase yield of milk and 4% fat-corrected milk for all cows, the milk yield was higher in 30 g/d groups during the whole experiment. There was a little tendency to increase percentage of milk fat, yield of milk fat and protein with RPC addition, while the percentages of milk lactose and total solids were similar among the four groups. The multiparous cows given 30 g/d of RPC produced significantly more milk (p<0.05) than those supplemented with 90 g/d RPC. Plasma concentrations of glucose remained at a higher level in 30 or 60 g/d RPC-supplemented groups, and NEFA decreased in the 30 g/d group. Concentrations of AST, ALT, triglycerides and cholesterol were not significantly different among the four groups. These results suggest that RPC addition tended to increase milk yield and improve blood metabolic parameters in transition dairy cows, and feeding 30 g/d of RPC may be the optimal.In Expt 5, the effect of dietary supplemental RPC and folic acid was investigated on milk performance and blood metabolic parameters during transition. Folic acid was fed with two levels of RPC to 60 multiparous dairy cows in a 3 x 2 factorial treatments. From 10 d before expected calving to 30 d postpartum, the cows received either 0,1.2, or 2.4 mg/d of folic acid per kg of body weight and either 0 or 30 g RPC per cow. Dry matter intake was not affected by addition of RPC or folic acid. Feeding of RPC or folic acid tended to increase milk yield, while 4% FCM decreased as cows received no RPC. Concentration of milk protein significantly reduced by RPC addition but the yield did not. No significant effects were observed on milk fat, milk lactose, total solids percentages and the yield. Plasma concentrations of AST and NEFA tended to be lower in cows consumed RPC, while the concentrations of ALT and triglycerides were similar among the groups. A moderate fatty infiltration in the liver occurred in two groups added with only folic acid and one group with RPC addition. Compared to folic acid groups, feeding of RPC tended to produce higher plasma concentrations of glucose and lower P-hydroxybutyrate acid during the experiment, while plasma concentrations of plasma urea nitrogen was not significantly different among treatments. Little incidence of health disorders was observed in RPC groups. These results suggest that RPC is beneficial for transition dairy cows, and lactational response to folic acid addition seems limited.In summary, compared to trundle pan coating method, pelleting can protect choline chloride from solubility more effectively. Choline chloride with silica supporter was protected better.than that with the vegetable supporter. The protection rate of choline by once pelleting was higher than twice pelleting. The pelleted choline can be effectively digested in the ruminant and the estimated whole tract digestibility of choline from the pelleted samples was above 95%. The RPC is beneficial for milk performance and plasma metabolic parameters.