|VILLALBA, J - Utah State University|
|CABASSU, R - Utah State University|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2015
Publication Date: 5/1/2015
Publication URL: http://handle.nal.usda.gov/10113/61322
Citation: Villalba, J.J., Cabassu, R., Gunter, S.A. 2015. Forage choice in pasturelands: influence on cattle foraging behavior and production. Journal of Animal Science. 93:1729-1740.
Interpretive Summary: Research of grazing animals has shown that they mix dietary species of plants to optimize the diet within the restraints of the sward composition. Pastures are often planted as monocultures of grass because the timing of management actions is simplified compared to mixtures of grasses and forbs. These monocultures of grass are easily managed, but create problems associated with dietary nutrient imbalances during various times of the year, especially during periods when the grasses are dormant. We determined if trinary mixtures of grasses and forbs would lead to complementary relationships that positively influence the grazer’s behavior and performance. In our research, cattle grazed monocultures of tall fescue, alfalfa, sainfoin, or a choice of any of the three (forages planted in three strips). Cattle on the mixture and the sainfoin showed the least number of grazing sessions each day. Cattle grazing the mixed pastures chose to graze sainfoin the most and tall fescue the least. Further, cattle on the mixed and tall fescue pastures walked further than cattle grazing the other two monocultures. Fecal crude protein analysis indicated that cattle on pastures with forbs had a superior protein intake compared to tall fescue. Cattle grazing the mixtures were more active, displayed lower number of grazing bouts, and had comparable average daily gain with cattle grazing either monoculture of legume. Thus, forage diversity within a pasture may lead to superior animal productivity compared to monocultures of legumes or grasses and reap the benefit of the symbiotic relationship of atmospheric nitrogen fixation by legumes that nourish the grasses.
Technical Abstract: We determined if trinary combinations of plants led to complementary relationships that influenced animal behavior and performance over combinations of lower diversity (monocultures). Grazing bouts, behavioral levels of activity, blood urea nitrogen, chemical composition of feces, body weight, and herbage biomass before and after grazing were monitored when cattle strip-grazed three replications of four treatments from June 14 through August 23, 2013 (9 animals/replication). Cattle grazed monocultures of: 1) tall fescue (TF), 2) alfalfa (ALF), 3) sainfoin (SAN), or 4) a choice of strips of forages TF, ALF, and SAN (CHOICE). The lowest and greatest incidence of foraging bouts occurred for cattle in CHOICE and SAN, respectively (P < 0.01). Animals in CHOICE spent the scan-sampling sessions grazing SAN > ALF > TF (P < 0.01). Animals on TF and CHOICE took a greater number of steps than calves grazing a monocultures of either legume (P = 0.01). Animals in TF had lower blood urea nitrogen (P < 0.01) and fecal crude protein concentration (P < 0.01) than animals grazing the remaining treatments, whereas animals in SAN showed the greatest concentrations of fecal CP (P < 0.01). Fecal neutral detergent fiber concentration was the greatest for cattle grazing TF and the lowest for cattle grazing SAN (P < 0.01), whereas fecal acid detergent fiber concentration was greater for animals grazing TF and SAN than for animals grazing CHOICE and ALF (P = 0.02). Calcium, magnesium, and zinc concentrations were the lowest in feces from animals grazing TF and the greatest for cattle grazing a monoculture of either legume (P < 0.05). Cattle grazing SAN, ALF, or CHOICE gained more BW than cattle grazing TF (0.3 kg/d) (P < 0.01). Cattle grazing CHOICE were more active, displayed lower number of grazing bouts, and had comparable ADG than cattle grazing either monoculture of legume. Thus, forage diversity may lead to levels of secondary productivity comparable to legume monocultures with the benefit of maintaining plant species diversity in pasturelands.