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.

Item	AHD	ATD	THD	SEM	P-value
Performance data (kg/d)(n = 62 cows per pen)
DMI	21.1	20.5	20.6	0.81	0.42
NDF intake	5.9b	6.2a	6.3a	0.24	<0.01
Milk yield	37.7a	37.2a	35.9b	0.68	<0.01
Milk fat yield	1.44a	1.44a	1.41b	0.10	0.06
Milk protein yield	1.22a	1.19b	1.15c	0.02	<0.01
N balance (g/d)(n = 8 cows per pen)
N intake	616a	598ab	593b	18.5	0.09
Milk N	192a	186a	180b	3.4	<0.01
Urinary N	215	225	221	12.8	0.57
Fecal N	197	192	192	9.8	0.81

 Unaccounted N 12.8 −6.2 0.5 23.4 0.29 ^a,b,cMeans with different superscript differ (P ≤ 0.05).