Abstract #M235

Section: Ruminant Nutrition (posters)
Session: Ruminant Nutrition I
Format: Poster
Day/Time: Monday 7:30 AM–9:30 AM
Location: Exhibit Hall A

# M235
Assessing three levels of a rumen-protected methionine prototype on dairy cow performance.
Amanda M. Barnard^*1, MacKenzie Conklin¹, Kari Estes², Barbara A. Barton², Clay Zimmerman², Tanya F. Gressley¹, ¹Department of Animal and Food Sciences, College of Agricultural and Natural Resources, University of Delaware, Newark, DE, ²Balchem Corp, New Hampton, NY.

Differences in the encapsulation technology used to protect methionine products may affect their rumen degradation and intestinal availability. The objective of this study was to determine the effect of a lipid encapsulated methionine prototype on milk, milk protein and casein yields. The study was conducted as a replicated 5 × 5 Latin square design with 5 multiparous and 5 primiparous Holstein cows assigned to either a negative control ration (NC) deficient in metabolizable (MP) methionine (−16.2 g/d), NC supplemented with Smartamine M (SM, Adisseo, Antony, France) or the NC supplemented with a methionine prototype containing 70% D,L-methionine at 3 different inclusion levels (M1, M2, M3, Balchem Corporation, New Hampton, NY) containing 100, 125, and 150%, respectively, of methionine that is in Smartamine M. The ration was balanced using NDS assuming 28 kg/d DMI, 50 kg/d milk, 3.80% fat, 2.90% protein, and 707 kg BW. Periods were 14 d and milk samples were collected on d 11–14 of each period. Data collected during the last 4 d of each period were averaged by cow and analyzed using the Glimmix procedure of SAS. The model included a covariate (data collected during a 2-week standardization period), fixed effects of treatment, period, parity and the interaction of treatment × parity and the random effect of cow. Treatment affected protein percentage (P = 0.03) and casein percentage (P = 0.05; Table 1). Compared with the NC, SM, M2 and M3 treatments increased protein percentage and casein percentage suggesting that the M2 and M3 treatments were equally as effective as Smartamine M. Table 1. Effect of methionine supplementation on production measures

Item	Treatment					SEM	P-value
NC	SM	Methionine prototype
M1	M2	M3	Treat	Parity	Treat × Parity
DMI, kg/d	26.4	26.1	26.1	26.2	25.0	0.9	0.37	0.80	0.14
Milk, kg/d	39.9	39.9	38.8	40.5	39.4	0.9	0.55	0.04	0.44
ECM, kg/d	40.0^AB	40.1^AB	38.7 ^B	41.0^A	40.0^AB	0.7	0.08	0.004	0.27
Protein, %	2.89^B	2.98^A	2.94^AB	2.95^A	2.96^A	0.03	0.03	0.42	0.75
Protein, kg/d	1.14	1.19	1.13	1.19	1.16	0.03	0.29	0.06	0.60
Casein, %	2.26^B	2.34^A	2.31^AB	2.32^A	2.32^A	0.03	0.05	0.35	0.84
Casein, kg/d	0.89	0.93	0.89	0.93	0.91	0.02	0.29	0.07	0.51

Key Words: bovine, methionine, milk protein