Search

The objective of this study was to determine if increasing forage botanical diversity improved stocker gains on warm-season annual (WSA) pastures. An opportunity exists to add extra gain on fall-born calves by grazing summer pastures after spring weaning and selling at a more favorable late summer market. However, cool-season perennial pastures in the Mid-South often have insufficient quality and yield to support desired summer gains. Therefore, the improved production and nutritive value of WSA forages shows promise in this system. A study was conducted near Princeton, KY, where calves (329, 366, and 297 kg in 2017, 2018, and 2019, respectively) grazed one of three WSA forage treatments without supplementation in a randomized complete block design with three replications. Treatments included 1) sorghum-sudangrass monoculture (MONO), 2) simple mixture (SIMPLE = sorghum-sudangrass, pearl millet, soybean), and 3) complex mixture (COMPLEX = SIMPLE + sudangrass, corn, crabgrass, cowpea, sunflower, sunn hemp, daikon radish, forage rape, Korean lespedeza). In 2017, MONO and SIMPLE calves had higher average daily gain (ADG) than COMPLEX calves (0.79 kg/day vs. 0.66 kg/day, P < 0.03). In 2018, no differences in ADG were detected among treatments (P > 0.3); however, calves only gained 0.01 kg/day. In 2019, MONO and SIMPLE calves again had higher ADG than COMPLEX calves (0.59 kg/day vs. 0.43 kg/day, P < 0.03). The exceptionally low 2018 ADG was likely due to the higher nutritional demand of heavier calves and the lower nutritive value of mature forages compared to other years. In conclusion, complex WSA forage mixtures did not offer any improvement in animal performance, and proper management of all WSA forages (maintaining a vegetative state) is paramount to achieving adequate gains on stockers without supplementation; however, supplementation may be necessary to improve WSA forage utilization in the rumen, potentially leading to more favorable gains. [ABSTRACT FROM AUTHOR]

Relationships of forage nutritive value (NVAL) and quantity with individual animal performance on pasture have long been evaluated, but there have been few attempts to describe the specific roles or relative importance of NVAL and quantity in determining animal response. The objective of this review was to more clearly define these roles based on a comprehensive assessment of pastureland literature and the application of a meta-analysis. It is clear that quantity and NVAL interact. When pastures present a wide range in forage mass, 60 to 90% of variation in average daily gain (ADG) can be explained by quantity, but there may be no relationship of NVAL with ADG. If pastures present only high forage mass, there may be no relationship between quantity and ADG, but NVAL may explain more than 50% of variation in ADG. The meta-analysis and a review of studies that evaluated forages of differing NVAL across a range of forage mass provided evidence that NVAL (i) sets the upper limit for ADG, (ii) determines the slope of the regression of ADG on stocking rate (SR), and (iii) establishes the forage mass at which ADG plateaus. In contrast, forage quantity determines the proportion of potential ADG that is achieved and is the primary driver for direction of the ADG response (negative) to increasing SR. Thus, the literature supports a conclusion of interaction among forage NVAL and quantity in affecting individual animal performance on pasture, but it suggests that the roles of each are quite well defined. [ABSTRACT FROM AUTHOR]