In this study, the feeding behavior of Nellore heifers receiving supplements containing mineral salt, conventional urea and slow release urea during the grazing stage at Brachiaria brizantha-based pastures during the dry period of the year was evaluated. Fifty-six heifers with approximately 284.72 ± 27.48 kg of body weight were used, distributed in a completely randomized design with four different treatment types: mineral salt; Urea - supplementation with 8.18% conventional urea; Mixed urea - supplementation with 4.09% conventional urea and 4.39% slow release urea and slow urea - supplementation with 8.78% slow release urea. Animals supplemented with mineral salt had longer grazing times compared to those supplemented with mixed urea, slow urea and regular urea. The dry matter intake, neutral detergent fiber and total digestible nutrients presented a similar effect, with higher values for heifers consuming supplements containing regular urea and slow urea compared to those of mixed urea. However, when the efficiency of hourly intake was evaluated, the animals that received urea supplement were more efficient in relation to the other treatments. The number of grazing periods for heifers receiving slow urea supplementation was higher compared to heifers receiving salt and mixed urea. The duration of grazing and rumination periods was longer for heifers receiving salt supplementation and mixed urea than those receiving regular urea and slow urea. It is recommended to use supplements at the level of 0.3% of body weight for heifers receiving conventional urea.

This study evaluated the feeding behavior of lactating cows on pasture of Brachiaria (Urochloa) decumbens fed with concentrate supplementation containing different levels of castor meal inclusion treated with calcium hydroxide Ca (OH) 2, in the proportions of 0; 3.3; 6.6 to 10% of the total diet. Eight cows (degree of blood ½ to ¾ Holstein x Zebu), with previous average production of 3000-4000 kg adjusted to 300 days of lactation and average body weight of 465.16 kg ± 65.45 kg were distributed in two 4 x 4 Latin squares. The behavior was assessed every five minutes for 24 hours on the 21 st day of each period. The results were tested by analysis of variance and regression at p < 0.05 probability. The time spent in grazing, rumination, idle and in the trough; total chewing time, number of cuds per day, chewing per day; chewing per cud; the number of periods of grazing, rumination, idle and in the trough; time spent by period of grazing, rumination, idle and in the trough were not different between treatments. The feed efficiency (g DM h -1 ; g NDFa h -1 and g TDN h -1 ) and time spent per cud ruminated TSR sec cud -1 ) were linearly reduced. It is recommended to include up to 10% castor meal treated with Ca (OH) 2 in the total diet. Key words: Bite. Co-product. Pasture. Ruminant. ResumoObjetivou-se avaliar o comportamento ingestivo de vacas leiteiras em pastagem de Brachiaria (Urochloa) decumbens submetidas a suplementação concentrada com diferentes níveis de inclusão de farelo de mamona tratada com hidróxido de cálcio Ca(OH) 2 , nas proporções de 0; 3,3; 6,6 e 10% na dieta total. Utilizaram-se oito vacas (grau de sangue ½ a ¾ Holandês x Zebu), com produção média anterior entre 3.000 a 4.000 kg, ajustada para 300 dias de lactação e peso corporal médio 465,16 kg ± 65,45 kg. cinco minutos, durante 24 horas no 21º dia de cada período. Os resultados foram submetidos a análises de variância e regressão a 0,05 de probabilidade. Os tempos despendidos nas atividades de pastejo, ruminação, ócio e cocho; tempo de mastigação total, número de bolos ruminados por dia, mastigação por dia; mastigação por bolo; o número de período de pastejo, ruminação, ócio e cocho; tempo gasto por período de pastejo, ruminação, ócio e cocho não houve diferença entre os tratamentos. A eficiência de alimentação (em g MS h -1 ; g FDNc h -1 e g NDT h -1 ) e tempo gasto por bolo ruminado TRB seg bolo -1 reduziram linearmente. Recomenda-se a inclusão de até 10% de farelo de mamona tratada com Ca(OH) 2 na dieta total. Palavras-chave: Bocado. Coproduto. Pastagem. Ruminante.