ABSTRACT. The objective of this study was to evaluate correlations between production and economic variables of lactating cows on a tropical pasture. The experiment involved ten ¾ Holstein × ¼ Dairy Gyr cows in the middle third of lactation at an average age of 70 ± 4.6 months and an average body weight of 400 ± 55.2 kg. Cows were supplemented with a concentrate feed with different supplement compositions aiming to promote alterations in the animal performance and economic responses. Data were analyzed statistically by Pearson correlations at the 0.95 probability level. No correlations were observed for fat and total solids with economic variables (p > 0.05). Milk yield was positively correlated with (p < 0.05), but had no correlation with FC or MRR (p > 0.05). There were no correlations for milk yield with RC, FC, or MRR (p > 0.05). Positive correlations were observed for fat corrected milk yield with GRSM and RMSC (p < 0.05). Fat production (kg day ) was positively correlated with GRSM and RMSC (p < 0.05). The gross revenue from the sale of milk and the revenue minus feed costs showed to be highly associated with production variables.Keywords: composition; interaction; milk; pasture; relationship; ruminant.Correlações entre variáveis produtivas e econômicas em vacas lactantes em pastagem tropical RESUMO. Objetivou-se avaliar correlações entre variáveis produtivas e econômicas em vacas lactantes em pastagem tropical. Foram utilizadas 10 vacas lactantes (¾ Holandesa x ¼ Gir Leiteiro), no terço médio de lactação, com idade média de 70 ± 4,6 meses e peso corporal médio de 400 ± 55,2 kg. Estes animais foram suplementados com ração concentrada com diferentes composições do suplemento, visando promover alterações na resposta animal e econômica. Os dados foram analisados estatisticamente por meio de correlações lineares de Pearson a 0,95 de probabilidade. Não foram observadas correlações entre gordura e extrato seco total com as variáveis econômicas (p > 0,05). A produção de leite correlacionou-se positivamente com RBVL e RMCS (p < 0,05). A produção de leite não se correlacionou com o CALI e TRM (p > 0,05). Houve ausência de correlações entre produção de leite corrigida e CVOL, CALI e TRM (p > 0,05). Foram observadas correlações positivas entre produção de leite corrigida com RBVL e RMCS (p < 0,05). Houve correlações positivas entre produção de gordura (kg dia -1 ) com RBVL e RMCS (p < 0,05). A receita bruta com a venda do leite e a receita menos custo com alimentação demonstraram estar altamente associadas com as variáveis produtivas.

The objective of this study was to evaluate productive, nutritional, and economic traits in lactating cows on pasture fed diets with different cation-anion balances (DCAB). Ten lactating ¾ Holstein × ¼ Dairy Gyr cows in the middle third of lactation, at an average age of 70 ± 4.6 months and an average body weight of 400 ± 55.2 kg, were distributed into five treatments in a 5 × 5 Latin square experimental design with two simultaneous squares. Treatments consisted of diets with DCAB of +237, +258, +294, +347, or +419 mEq dry matter (DM). No effects of intake were observed. There was no significant effect of DCAB on milk yield. The milk protein content was not influenced by the DCAB. Body condition score was not significantly affected by the DCAB. The apparent digestibilities of dry matter and nutrients (crude protein, neutral detergent fiber, ether extract, non-fibrous carbohydrates, and total digestible nutrients) were not affected by the DCAB. Marginal rate of return did not show significant differences. Under good conditions of pasture, forage availability, and quality associated with the lactation phases of the cows, all diets were efficient in milk production, dry matter intake, and digestibility. However, in economic terms, the most attractive DCAB was +237 mEq kg-1 DM.

The objective of this study was to evaluate productive traits in sheep fed roughage-free diets by multivariate analysis. Forty lambs were used in this study: 20 Santa Inês animals, consisting of 10 uncastrated males and 10 females; and 20 crossbreds (½ Santa Inês × Dorper), consisting of 10 uncastrated males and 10 females, at an average age of five months. Lambs were randomly allocated into the following treatments: Santa Inês males fed once daily (SM1); Santa Inês males fed twice daily (SM2); Santa Inês females fed once daily (SF1); Santa Inês females fed twice daily (SF2); crossbred males fed once daily (CM1); crossbred males fed twice daily (CM2); crossbred females fed once daily (CF1); and crossbred females fed twice daily (CF2). In the multivariate analysis, a difference was detected between the mean values for production classes and feeding-behavior variables (Wilks, Pillai, Hotelling-Lawley, and Roy tests). Tocher's optimization method had two groups formed: Group I, comprising treatments SM1, SM2, SF1, SF2, CF1, and CF2; and Group II, containing treatments CM1 and CM2 (crossbred males). When production and cud chews per day were evaluated, neutral detergent fiber digestibility and final weight were the performance-digestibility variables that most contributed to explaining the variation between treatments. When the feeding behavior was assessed, the time spent on other activities was the variable that most contributed. The crossbred genotype (½ Santa Inês × Dorper) and the male sex have superior performance for weight-related traits. However, when these animals are confined with females, it is recommended to supply the feed only once daily, irrespective of the genetic group.

The objective of this study was to evaluate linear correlations between feed intake and ingestive behavior of feedlot lambs. Were used ten castrated male Santa Inês sheep with a body weight of 20 ± 4.38 kg, at four months of age. The experiment lasted 50 days, with five 10-d periods, in which an evaluation of feed intake and ingestive behavior was undertaken per period, totaling 50 replicates. The diet was composed of concentrate ingredients only. The analyses were performed by Pearson’s linear correlations and the t test, and means were considered significant when P≤0.05. Intake showed positive correlations (P≤0.05) with the times spent feeding and ruminating and total chewing time, and a negative correlation (P≤0.05) with other activities. Positive correlations were found between the number of feeding periods, number of other activities and the time per rumination period with intake (P≤0.05). A negative correlation was found between the feed efficiency of dry matter and the intake, as well as the other nutrients (P≤0.05). The behavioral characteristics related to feed intake appear to be correlated, which allows for inferences through the study of these variables. The activities related to nutrient intake, with respect to time and efficiency, can be expressed directly through the animal behavior.

This study aimed to evaluate the feeding behavior of Santa Inês ram lambs in the feedlot receiving diets without roughage in different amounts. Ten castrated Santa Inês male sheep with an average body weight of 20 kg and an average age of four months were used in the experiment. The following treatments were tested: T1 - animals receiving a diet ad libitum (FS100); T2 - animals receiving 95% of the amount of feed supplied in T1 (FS95); T3 - animals receiving 90% of the amount supplied in T1 (FS90); T4 - animals receiving 85% of the amount supplied in T1 (FS85); and T5 - animals receiving 80% of the amount supplied in T1 (FS80). A Latin square (5 × 5) design was adopted, using two simultaneous squares. The times spent feeding, ruminating, performing other activities; the total chewing time; and the number of periods spent feeding and on other activities changed with the reduction in the amount of feed supplied (P<0.05). Number of rumination chews per cud, time per cud, chewing speed, and time per rumination chew did not differ with the reduction of feed supply (P>0.05). Reducing the amount of feed provided to ram lambs consuming diets without roughage changes their feeding behavior.