This experiment was conducted in order to evaluate the effect of undegradable dietary protein (UDP) level on milk production and composition of 24 lactating dairy cows. Treatments consisted of T0: ) control diet without UDP (forage and concentrate were offered in total mixed ration); T1: control diet without UDP (forage and concentrate were offered separately); T2: control diet + UDP 40 gr/L milk + mineral mix; and T3: control diet + UDP 60 gr/L milk + mineral mix. Data were analyzed using analysis of variance (ANOVA) and the differences between treatment means were examined by duncan multiple range test (DMRT). The results showed that UDP supplementation significantly (p<0.05) affected nutrient consumption (dry matter, organic matter, crude protein and total digestible nutrient). In addtion, UDP supplementation significantly increased milk production and 4% FCM production (p<0.05). A higher level of milk production and 4% FCM yielad in animals fed with T2 and T3. Thus, UDP supplementation may be an alternative supplement for the lactating dairy cows.

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Dairy cows often experience heat stress in the tropics. Tunnel ventilation technology reduces heat stress in dairy cow housing. Here, we examined the performance of tunnel-ventilated barns on the physiological responses, milk yield, and dry matter intake of dairy cows during the wet season in a tropical area. The experiment was conducted on a commercial dairy farm in Malang, Indonesia from mid December 2017 until mid January 2018. Lactating Friesian Holstein cows (n = 661) were studied in two barns of different dimension, with cooling treatments. Air temperature, relative humidity, and air speed were measured. Respiration rate, lying down percentage, milk yield, and dry matter intake were analyzed in response to modified environmental conditions. Data were analyzed with independent sample t tests using SPSS ® Statistics 24 for Windows. Outisde and inside air speeds for both barns (P < 0.05) showed significant difference. Surprisingly, no differences were found for temperature (T), relative humidity (RH), and temperature-humidity index (THI) between the outside and inside for both barns (P > 0.05). A significant difference was noted in milk yield, dry matter intake (DMI), respiration rate (RR), and lying down percentage (LDP) (P < 0.05). Thus, the tunnel-ventilated barn performed better and air speed was better distributed inside the barn. However, the barn had environmental conditions similar to those outside. Dairy cows showed high RR as milk yield and DMI increased. In the future, lying down behavior of dairy cows in response to cooling treatments in the tropics needs to be further studied.