Abstract #T224

# T224
Effect of replacing alfalfa hay with triticale hay on milk production and nitrogen metabolism in dairy cows.
O. Santana*1, J. Olmos-Colmenero2, M. Wattiaux1, 1University of Wisconsin-Madison, Madison, WI, 2Centro Universitario de los Altos, Universidad de Guadalajara, Tepatitlán, Jalisco, México.

Triticale is a less water-intensive crop than alfalfa and could become an alternative source of high crude protein (CP) forage on dairy farms located in water shortage areas. Our objective was to evaluate the effect of replacing alfalfa hay (AH) with triticale hay (TH) on milk production and N metabolism in mid-lactation Holstein cows. The study was conducted on a commercial farm in Jalisco, Mexico, where 12 pens (experimental units) were allocated to 3 treatments in 4 3 × 3 Latin Square where each square was a separate barn. Each pen had 62 cows (54 primiparous and 8 multiparous; 124 ± 34 d in milk and 578 ± 21 kg body weight). Diets (17.4% CP, 1.68 Mcal/kg, and 29.1% neutral detergent fiber (NDF), dry matter (DM) basis) included 25.6% corn silage and either 16.4% AH (AHD), 9.0% AH and 7.6% TH (ATD), or 16.4%TH (THD). Pen values for performance data were from all cows in each pen but N metabolism data were from 8 cows per pen. Nitrogen balance was based on fecal and urine spot sampling. Results in Table indicated no differences in DM intake but higher NDF intake and lower milk protein yield with TH in the diet. Milk and milk fat yields declined only with the highest level of TH in the diet. No difference was detected for milk urea-N (12.4 ± 0.19 mg/dL; P = 0.56) or N use efficiency (milk N / intake N; 30.9 ± 1.03%, P = 0.32). The N balance data showed similar N intake and milk N for cows fed AHD and ATD, but depressed values for cows fed THD. There were no differences for fecal N and urinary N. Findings suggested similar efficiency of N utilization, but restriction in energy supply associated with rumen fill when TH replaced AH in the diet. Table 1.
 Performance data (kg/d)(n = 62 cows per pen)
 NDF intake5.9b6.2a6.3a0.24<0.01
 Milk yield37.7a37.2a35.9b0.68<0.01
 Milk fat yield1.44a1.44a1.41b0.100.06
 Milk protein yield1.22a1.19b1.15c0.02<0.01
 N balance (g/d)(n = 8 cows per pen)
 N intake616a598ab593b18.50.09
 Milk N192a186a180b3.4<0.01
 Urinary N21522522112.80.57
 Fecal N1971921929.80.81
 Unaccounted N 12.8 −6.2 0.5 23.4 0.29 a,b,cMeans with different superscript differ (P ≤ 0.05).

Key Words: alfalfa, triticale, dairy