Abstract
The objectives of this study were to compare visual observation and an electronic grazing time method and to evaluate the effects of nutritional plans on intake, grazing behavior and horizontal and vertical locomotion of young bulls in a tropical pasture. Thirty-nine Nellore young bulls with an average body weight of 345±9.3 kg kept in pasture were used. The experimental treatments consisted of: restricted: animals kept in a plot with a low mass of forage receiving mineral mixture only; control: animals receiving mineral mixture only; HPHC: a high protein and high carbohydrate supplement; HPLC: a high protein and low carbohydrate supplement; LPHC: a low protein and high carbohydrate supplement; LPLC: a low protein and low carbohydrate supplement. GPS collars equipped with activity sensors were used. Information about head position, latitude, longitude and altitude were recorded. Daytime grazing behavioral patterns monitored by a continuous focal animal recording method was compared to behavior estimated by the activity sensor. Feed intake was estimated by a marker method. The Restricted group presented lower (p<0.05) intake of dry matter and TDN. However, difference in dry matter intake was not found (p>0.05) between non-supplemented and supplemented animals. Difference was not found (p>0.05) in daytime grazing time obtained by visual observation or the activity sensor method. The restricted group showed longer (p<0.05) grazing time (9.58 h/d) than other groups, but difference was not found (p>0.05) in the grazing time between Control (8.35 h/d) and supplemented animals (8.03 h/d). The Restricted group presented lower (p<0.05) horizontal locomotion distance (2,168 m/d) in comparison to other groups (2,580.6 m/d). It can be concluded that the use of activity sensor methods can be recommended due to their being similar to visual observation and able to record 24-h/d. While supplements with high carbohydrates reduce pasture intake, they do not change grazing behavior. Moderate supplementation (until 50% of protein requirement and 30% of energy requirement) of beef cattle on tropical pasture has no effect on daily locomotion.
Highlights
The use of electronic equipment to monitor cattle and the spatial distribution of animals
Where: FE is the fecal excretion; iNDF feces is the concentration of iNDF in the feces; iNDF supplement is the amount of iNDF in the supplement; iNDF forage is the concentration of NDFi in the forage; and SI is the supplement intake
The forage sampled by hand plucked sampling was considered high quality forage, presenting up to 10.7% of crude protein (CP) (Table 1) which is higher than the level of CP (9%)
Summary
The use of electronic equipment to monitor cattle and the spatial distribution of animals. Sci. 26:1717-1725 or relayed to external memory (Johnson and Ganskopp, 2008) It is possible get information of the locomotion (horizontal and vertical) of the animals. Cattle try to minimize expended energy in grazing activity and maximize energy returns They do not always optimize nutrient intake during a meal or on a daily basis (Distel et al, 1995). Supplementation affects forage intake, pasture utilization efficiency (Valente et al, 2011a), and animal behavior (Casagrande et al, 2011). The objectives of this study were to compare visual observation and electronic methods of evaluation of grazing time and to evaluate the effects of nutritional planning on intake, grazing behavior and the horizontal and vertical locomotion of young bulls in a tropical pasture
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