The objective of this study was to validate an electronic system for monitoring individual feeding behavior and feed intake (Intergado Ltd., Contagem, Minas Gerais, Brazil) in freestall-housed dairy cattle. No data have been published that validate either the behavioral measurement or the feed intake of this system. Feeding behavior data were recorded for 12 Holstein cows over 5d using an Intergado system and time-lapse video. The cows were fitted with an ear tag containing a unique passive transponder and provided free access to 12 feed bins. The system documented the visit duration and feed intake by recording the animal identification number, bin number, initial and final times, and the difference between feed weight at start and end of each feed bin visit. These data were exported to Intergado web software and reports were generated. Electronic data on animal behavior were compared with video data collected during the same evaluation period. An external scale was used to manually measure and validate the electronic system's ability to monitor dairy cow feed intake for each feed bin visit. The feed intake was manually measured for 4-h time periods and compared with the sum of the feed intake recorded by the monitoring system for each cow visit during the same time period. Video and manual weight data were regressed on the electronic feeding behavior and feeding intake data to evaluate the precision of the monitoring system. The Intergado system presented high values for specificity (99.9%) and sensitivity (99.6%) for cow detection. The visit duration and feed intake per visit collected using the electronic monitoring system were similar to the video and manual weighing data, respectively. The difference between the feed intake measured manually and the sum of the electronically recorded feed intake was less than 250g (25,635±2,428 and 25,391±2,428g estimated using manual weighing and the electronic system, respectively). In conclusion, the Intergado system is a reasonable tool to monitor feeding behavior and feed intake for freestall-housed dairy cows.

Genetics differences between breeds may determine the tolerance to high temperature, effect dry matter intake and consequently cattle performance. The effect of temperature and humidity index (THI) on diurnal, nocturnal and daily intake, water intake, physiologic parameters and behavior of Nellore (B. indicus) and Angus (B. taurus) bulls were evaluated. Eight Angus and eight Nellore young bulls (337±7.4 kg and 16 months of age) were allocated in two climate-controlled rooms for 32 days. In the period 1, all bulls were housed in thermoneutral conditions (TN, THI = 72.6) for 10 days. In period 2 (10 days), four Angus and four Nellore bulls were subjected to low heat stress (LHS, THI = 76.4) in daytime, and four Angus and four Nellore bulls were subjected to high heat stress (HHS, THI = 81.5) in daytime. The diurnal and daily dry matter intake (DMI) of Nellore were not affected (P>0.05) by heat stress. However, Angus bulls decreased diurnal DMI by 24% and daily DMI decreased (P<0.05) by 15% on HHS. In TN Angus bulls had higher (P0.05) daily DMI (31.6 and 30.2 g/kg of BW, respectively). We observed an increase (P0.05) by heat stress. The heart rate decreased (P0.05) in feeding behavior. Therefore, THI stress threshold should distinct for Angus and Nellore bulls. The use of feed intake information may improve the prediction of thermic discomfort on specific climate condition.

The objective of this experiment was to evaluate the effect of providing different levels of a supplement on the nutritional characteristics and productive performance of heifers on pasture during the rainy-dry transition and dry season in Brazil or tropical area. Thirty crossbred heifers with predominance of Zebu breed were used in a completely randomized experimental design. Treatments consisted of a mineral supplement and 0.5, 1.0, 1.5, or 2.0 kg/animal/d of a protein supplement containing 300 g crude protein (CP)/kg of dry matter (DM). In the rainy-dry transition season there was quadratic effect of the protein supplementation (p0.10); the microbial efficiency (g CPmic/kg TDN) and the relationship of microbial nitrogen flow with nitrogen intake (g/g nitrogen intake) were negative linear profiles. In the dry season, the descriptive pattern least squares means showed a trend of stabilization of DWG from the supply of 0.98 kg of protein supplement; the intakes of DM, OM, CP, EE, NFC, and TDN showed increasing linear relationship (p<0.10) with protein supplement levels; the means of apparent digestibility coefficients of the different dietary fractions presented a linear-response-plateau (LRP); the microbial nitrogen flow (g/d) showed positive linear profile (p<0.10) for supplementation levels. It is concluded that supplementation improves the productive performance of grazing heifers and that 1.0 kg/d of supplement per animal gives the maximum increment of weight gain.