domly to a balanced split-plot 5 x 5 Latin square design involving two ... Each square consisted of five concentrations of .... 2.1 (Degussa Huls Corp., Allendale.
140 Insulin plays a key role in re-coupling the IGFsomatotropin axis in the early postpartum dairy cow. S.T. Butler* and W.R. Butler, Cornell University, Ithaca, NY. Negative energy balance associated with the onset of lactation results in hypoinsulinemia, uncoupling of the IGF-somatotropin axis, attenuation of gonadotropin release and delayed first ovulation. Our objectives were to examine the effects of elevated insulin during the immediate postpartum period on circulating IGF-I concentrations, ovarian follicular growth, estradiol secretion and LH pulse profiles. Holstein cows (n=14) were subjected to either a hyperinsulinemic-euglycemic clamp (INS) or saline infusion (CTL) for 96 hours starting on day 10 postcalving. Blood samples were taken on days 8-9 to establish baseline glucose values. Insulin was infused continuously (1 µg/kg BW/hr) via a jugular catheter. Blood samples were collected hourly, and euglycemia was maintained by infusion of exogenous glucose. During infusion, insulin concentrations were increased 8-fold in INS cows over those in CTL cows (2.4 ± 0.1 vs. 0.3 ± 0.1 ng/ml; P 24 4.4
Coefficients
R2
SED
0.22
Key Words: Methionine, Rumen absorption, Chemical derivative
145 Feeding 2-hydroxy-4-(methylthio)-butanoic acid to transition dairy cows improves milk production but not hepatic lipid metabolism. M. S. Piepenbrink*1 , A. L. Bork1 , M. R. Waldron1 , T. R. Overton1 , M. Vazquez-Anon2 , and M. D. Holt2 , 1 Cornell University, Ithaca, NY, 2 Novus International, Inc., St. Louis, MO.
(HMB; Alimet feed supplement, Novus International, Inc. St. Louis, MO) on milk production and hepatic lipid metabolism during the transition period. Cows were fed one of three diets as TMR starting 21 d before expected calving. These diets contained 0 (CON), 0.1 (+HMB), or 0.21 (++HMB)% HMB. From parturition to 84 DIM, cows were fed diets that contained 0, 0.15, or 0.23% HMB. The CON diets were formulated to be low in Met (1.98 and 1.77% of MP for pre- and postpartum diets) but adequate in Lys (7.23 and 7.00% of MP for pre- and postpartum diets). Prepartum (12.9, 12.8, 12.7 kg/d) and postpartum (18.6, 19.8, 19.7 kg/d) DMI were similar among cows fed CON, +HMB, and ++HMB (P > 0.20). Feeding +HMB increased milk yield (42.0, 45.0, and 42.0 kg/d for CON, +HMB, ++HMB; P (quadratic) < 0.05). Percentages of fat, protein, and total solids in milk were not affected by treatment. Trends (P < 0.15) for increased yields of 3.5% FCM, lactose, and total solids by cows fed +HMB were related to milk yield. Differences in plasma NEFA (495, 514, 446 µEq/L) and β-hydroxybutyrate (13.72, 12.04, 11.92 mg/dl) were not significant (P > 0.25). Liver triglyceride content was similar on d 1 postpartum (7.24, 6.61, 6.75%) and was increased for +HMB on d 21 postpartum [(8.87, 13.68, 11.07%) treatment x d; P < 0.04]. Differences in rates of [1-14 C]palmitate oxidation [27.9, 23.7, 25.4 nmoles/(hour x g wet weight)], and formation into stored esterified products [318, 316, 338 nmoles/(hour x g wet weight)] were not significant. The data suggest that adding HMB to low Met but adequate Lys diets at 0.1% prepartum and 0.15% postpartum is beneficial for increasing milk production. The underlying mechanism does not appear to be associated with hepatic lipid metabolism as measured in this experiment. Key Words: HMB, Methionine, Liver
146 Use of milk protein concentrations to estimate the “methionine bioavailability” of two forms of 2-hydroxy4-methylthio butanoic acid (HMB) for lactating cows. C. G. Schwab*1 , N. L. Whitehouse1 , A. M. McLaughlin1 , R. K. Kadariya1 , N. R. St-Pierre2 , B. K. Sloan3 , R. M. Gill3 , and J. C. Robert4 , 1 University of New Hampshire, Durham, 2 The Ohio State University, Columbus, 3 Aventis Animal Nutrition, Alpharetta, GA, 4 Aventis Animal Nutrition, Antony, France. Forty multiparous Holstein cows (58 to 167 DIM) were assigned randomly to a balanced split-plot 5 x 5 Latin square design involving two replicates of four squares. Experimental periods were 14 d with the last 7 d for measurements. Each square consisted of five concentrations of a single methionine (Met) source in a Met-deficient diet. The four Met sources were: 1) Smartamine M-TM (SmM, Aventis Animal Nutrition), 2) HMB, 3) the isopropyl ester of HMB (HMBi), and 4) a combination of HMB and HMBi (HMB/HMBi). Treatment levels were (g Met equivalents/d per 25 kg of DMI): SmM (0, 10, 15, 20, and 25), HMB and HMBi (0, 15, 20, 25, and 30), and HMB/HMBi (0/0, 5/10, 8.3/16.7, 11.7/23.3, and 15/30). Because treatment levels within source were not spaced equally, appropriate orthogonal coefficients were generated using PROC IML of SAS. Corrected LSM for milk protein percentages were: SmM (2.99, 3.08, 3.15, 3.15, and 3.13; quadratic effect, P < 0.01), HMB (3.04, 3.02, 3.03, 3.06, and 3.03), HMBi (3.05, 3.11, 3.16, 3.17, and 3.19; linear effect, P < 0.001), and HMB/HMBi (3.07, 3.13, 3.12, 3.16, and 3.18; linear effect, P < 0.001). Inspection of the LSM indicated that a broken line model of response to Met sources was more adequate than smooth function models. Thus, PROC NLIN of SAS was used to identify the optimum level of supplementation (breakpoint) and the slope of the dose-response relationships prior to breakpoint for SmM, HMBi, and HMB/HMBi. Based on differences of slope, and the assumption that 80% of the Met in SmM is available, the bioavailability of Met from HMBi and HMB/HMBi was estimated to be 42% and 34%, respectively. Results indicate that HMB provided little or no Met for milk protein synthesis and that HMBi was 50% or more as effective as SmM. Key Words: Methionine, HMB, Ruminant
Forty-eight Holstein cows entering second or later lactation were utilized to determine the effects of 2-hydroxy-4-(methylthio)-butanoic acid
J. Anim. Sci. Vol. 79, Suppl. 1/J. Dairy Sci. Vol. 84, Suppl. 1/Poult. Sci. Vol. 80, Suppl. 1/54th Annu. Rec. Meat Conf., Vol. II
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147 Performance of high producing dairy cows fed methionine hydroxy analog or D, L-methionine in a total mixed ration during early lactation. K. Uchida1 , P. Mandebvu2 , C. J. Sniffen*2 , C. S. Ballard2 , and M. P. Carter2 , 1 Zen-Noh National Federation of Agricultural Co-operative Associations, Tokyo, Japan,, 2 W. H. Miner Agricultural Research Institute, Chazy, NY. Effect of feeding two methionine supplements was compared using high producing Holstein cows during early lactation. Pregnant cows housed in a free-stall barn at the Miner Institute in northeastern New York, were blocked and at calving, were assigned randomly to one of two TMR containing a liquid form of methionine hydroxy analog (MHA; Novus Intl., Atlanta, GA), or D,L-methionine (D,L-Met), and group-fed for ad libitum intake. Cows spent 3315 days in the fresh group (FG), after which they were moved to the high producing group (HG) where they stayed up to 8 wk postpartum. The TMR had on DM basis a forage to concentrate ratio of 40 to 60% for FG cows with predicted DMI of 21.7 kg/d, and 42 to 58% for HG cows with predicted DMI of 26.5kg/d. All TMR contained on DM basis 33% NDF and 18% CP. The TMR were formulated using the CPM Dairy# model to meet the methionine and lysine factorial requirement, and the methionine and lysine ratios of 2.20 and 6.89% of metabolizable protein, respectively. The concentrations of methionine and lysine, respectively, in all TMR were 0.25, 0.75 (% of DM). In order to provide the same amount of methionine postruminally from the two methionine supplements, cows fed TMR containing MHA and D,L-Met, respectively, were fed approximately 14.2 g of MHA and 25.7 g of D,L-Met for FG and 17.1 g of MHA and 31.0 g of D,L-Met for HG, assuming a rumen escape value of 40% for MHA and 22% for D,L-Met. The average daily DMI by the group-fed cows across treatments was 222.5 kg/cow for the FG, and 272.0 kg/cow for HG. Cows that were fed TMR containing MHA and D,L-Met, respectively, had similar (P>0.18) milk yield (49.0, 49.8 kg/d; SE=0.32), milk fat (4.03, 4.21%; SE=0.051), milk CP (3.13, 3.21%; SE=0.019), linear SCC (4.08, 4.55; SE=0.072), body condition score (3.17, 3.17; SE=0.019), days to first service (68.7, 65.1; SE=6.61), and first service conception rate (36.9, 35.0%) during wk 1 to 8 postpartum, and different milk fat (3.64, 3.93%; SE=0.07, P=0.07) during wk 5 to 8 postpartum. Average milk yield was 45.5 kg during wk 1 to 4 postpartum and 53.3 kg during wk 5 to 8 postpartum. In conclusion, D,L-Met performed as well as MHA in promoting milk yield and contents of milk fat and CP when fed at levels aimed at achieving similar amounts of methionine postruminally as supplied by MHA. Key Words: dairy cow, methionine hydroxy analog, milk yield and reproductive performance
148 Effect of two levels of crude protein and supplementation of methionine on performance of dairy cows. C. Leonardi*1 , L.E. Armentano1 , and M. Stevenson2 , 1 University of Wisconsin-Madison, 2 Degussa Canada Ltd., Ontario, Canada. Sixteen lactating Holstein cows (4 primiparous and 12 multiparous) were used in a 4 x 4 Latin Square, with periods of 35 days. At the beginning of the study animals averaged 95 DIM and produced 44.5 kg/d of milk. The effect of supplemental methionine at two levels of CP (16.1 vs. 18.8%) was tested. The two levels of protein and methionine supplementation were such that the lower level of CP supplemented methionine was sufficient to cover the requirements of amino acids, according to the Mepron Dairy Ration Evaluator ver. 2.1 (Degussa Huls Corp., Allendale NJ). The high level of protein (HP) was selected to meet the amino acids requirement without the supplementation of methionine. A low protein (LP) diet without methionine was added as negative control and the high protein diet plus methionine (HPM) as a positive control. All four diets contained 16.2% alfalfa silage, 38.6% corn silage, 16.2 % of corn grain, 8.1% soybean roasted, 5.7 % cottonseed, 2% soyplus, 1% blood meal, 0.8% animal fat, and 1.8 % minerals and vitamins mix (DM basis). The remaining 9.6% of the diet was either corn grain plus urea in the low protein diet, or soybean meal in the high protein diet. We anticipated an interaction where low protein responded to methionine more than the high protein diet, but no interactions were significant. The only methionine main effect was an increase in milk protein %, while increased dietary protein decreased milk protein %. Milk fat was depressed across diets. Low dietary NDF (27.2 % of DM), and high levels of vegetable oil (4.5 % fatty acids) may have been the cause of the low milk fat test. These dietary conditions may also have caused microbial protein synthesis to differ from the values predicted by the model used.
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A main effect of dietary protein was to elevate milk fat concentration and yield. -4
Treatments
DMI, kg/d Milk yield, kg/d Protein, % Protein, g/d Fat, % Fat, g/d MUN1 , mg/dl MUN, g/d Casein N/total N 1
-7
Effect (P-value)
LP
LPM HP
HPM SEM CP
Met
22.3 42.7 3.21 1361 2.27 949 10.44 4.44 .666
21.8 41.0 3.28 1330 2.39 958 10.60 4.29 .641
23.3 42.8 3.23 1373 2.65 1116 14.17 6.10 .691
.49 .63
