Inaugural ASAS–CAAV Asia Pacif ic Rim Conference Abstracts

M189 Influence of milk replacer pH on the development ofthe gastrointestinal tract of Chinese Holstein calves. Y. Tu*, Q.-Y. Diao, Y.Zhou, and Q. Yun, Institute of Feed Research, Chinese Academy of AgriculturalSciences, Beijing, P. R.China.The effect of reducing the pH of milk replacer solutions on the developmentof organs, chyme pH, and mucosal morphology of the gastrointestinal tractof Chinese Holstein calves was investigated. A total of 48 healthy neonatalChinese Holstein male calves were assigned randomly to 8 treatments (6calves/treatment) grouped in a 2 × 4 experimental design. Two milk replacerswere fed to calves, with plant protein percentages of total protein of 50% (A)and 80% (B), respectively, and the pH of their solutions were reduced from6.2 (1) to 5.5 (2), 5.0 (3), and 4.5 (4), each using 1 N HCl. All the calveswere fed in calf hutches. On d 56, three calves chosen randomly from eachgroup were killed, followed by collection of organs, chime, and mucosa ofthe gastrointestinal tract. Results indicated that the ratio of the weight of therumen, reticulum, omasum, abomasa, liver, spleen, thymus, and pancreas toBW was similar among all treatments (P > 0.05). The pH of the chyme from therumen, reticulum, and omasum were lower in treatment 4 (6.70, 6.74, and 6.49,respectively) than those in treatment 1 (6.98, 6.90, and 6.67, respectively; P 0.05). The villus height, crypt depth,ratio of villous height to crypt depth, and mucosal thickness of the duodenum,jejunum, and ileum in treatment 2, 3, or 4 did not differ significantly from thoseof treatment 1 (P > 0.05). Compared with treatment 1, the villous height andmucosal thickness of the jejunum and the villous height of the ileum were longerin treatment 2; the villous height of the jejunum was shorter in treatments 3 and4, and the villous height of the ileum was shorter in treatment 4 (P < 0.05). Itwas concluded that the development of the rumen was improved when the pHof milk replacer solutions was 5.0.Key Words: pH of milk replacer, calves, development of gastrointestinal tractM190 Effect of dietary supplementation with methioninehydroxy copper on teh performance of Holstein dairy cows. F. Wang, X.Jin, and S. Li*, State Key Laboratory for Animal Nutrition, College of AnimalScience and Technology, China Agricultural University, Haidiani, Beijing,China.Mintrex Cu is composed of 2 molecules of 2-hydroxy-4-(methylthio)butanoicacid chelated with 1 molecule of Cu. This study was conducted to investigatethe effects of different levels of Mintrex Cu supplementation on lactationperformance, blood biochemical parameters, nutrient digestibility, and serumbiochemical parameters in lactating cows, and to determine the suitable dose.Thirty clinically healthy lactating Holstein cow with similar milk yields,calving dates, and parities were assigned to the following 3 treatments: 1)control, 12 ppm of Cu in a premix supplemented with CuSO 4; 2) HSCu, 6 ppmof Cu supplemented by CuSO 4, and another 6 ppm by Mintrex Cu; 3) FSCu, 12ppm of Cu supplemented by Mintrex Cu. Ten replicates (1 cow as a replicate)were included per treatment. The trial lasted for 120 d, which included 20 dfor adaptation. The results were as follows. 1) During the trial, milk yield forall treatments generally declined, and milk yield of the HCu group (33.22 kg)was significantly higher than those of the control (29.73 kg) and FCu groups(31.43 kg). 2) Energy-corrected milk yield and lactose percentage of the HSCugroup were significantly higher than those of the control group (P < 0.05). 3)Acid detergent fiber digestion by the HSCu group increased compared withthe control group (P < 0.1), and the apparent digestibility of NDF increasedcompared with HSCu (P < 0.1). 4) Serum Cu concentration of the FSCu groupwas significantly higher (P < 0.05). Serum levels of Mn-SOD, LGH, TP, SUN,TC, HDL-C, LDL-C, TG, and Na of the FSCu group were the lowest, but notsignificantly lower (P > 0.05). The GLU concentration of the FSCu groupwas significantly lower than that of the HSCu group (P < 0.05). Serum CP,MAD, GSH-PX, T-SOD, ALB, K, and Ca of the FSCu group were betweenthe control and HSCu groups, and the difference was not significant (P > 0.05).It was concluded that the HSCu group could improve lactation performance,antioxidant ability, and antistress ability of cows. The diet of the FSCu groupprobably heavily burdened the liver, and 50% or lower Cu as Mintrex Cu isrecommended.M191 Impact of dietary cation-anion difference onperformance and acid-base status of early lactating dairy cows: A metaanalysis.B. Chen and J. Liu*, Institute of Dairy Science, Zhejiang University,Hangzhou, China.A meta-analysis was performed to examine the relationships between dietarycation-anion difference (DCAD; Na + K – Cl) and the production outcomes inearly-lactating dairy cows. The data were collected from 8 studies publishedbetween 1984 and 2008 that included a total of 10 trials, 23 dietary treatments,and 185 cows. Studies included in the data file met all the following criteria:(1) publications were in English; (2) the populations studied were earlylactatingdairy cows with days in milk