The objective was to evaluate water‐soluble carbohydrate (WSC) and crude protein (CP) concentration of perennial ryegrass (PRG) cultivars with different genetic potential for producing WSC under two contrasting agronomic managements in temperate climate (southern Chile). A 4 × 2 factorial design was randomly allocated to 24 plots (31 m2 each, three blocks): four PRG cultivars (diploid standard cultivar, “2nSt”; tetraploid standard cultivar, “4nSt”; diploid high sugar cultivar developed in New Zealand, “2nHSNZ”; and tetraploid high sugar cultivar developed in Europe, “4nHSEU”) and two agronomic managements (“favourable,” defoliations at three leaves per tiller and nitrogen (N) fertilization rate of 83.3 kg N ha−1 year−1; “unfavourable,” defoliations at two leaves per tiller and N fertilization rate of 250 kg N ha−1 year−1). Herbage samples were collected in early spring, spring, summer and autumn. Concentration of WSC did not differ among cultivars in spring and summer, averaging 194 and 251 g/kg DM, respectively. The cultivar 4nHSEU had the greatest WSC concentration in early spring and autumn (187 and 266 g/kg DM, respectively) and the greatest CP concentration across samplings (average 230 g/kg DM). Favourable management improved WSC concentrations in early spring and summer and decreased CP in spring, summer and autumn. Annual DM yield did not vary with cultivar or management, averaging 8.43 t/ha. Within a 12‐month study at one site in a temperate environment in southern Chile, PRG cultivars have not shown a consistent expression of the “high sugar” trait, where a genetic × environment interaction might be operating.
The objective of this study was to assess the joint effect of perennial ryegrass cultivars and drying methods on concentrations of water-soluble carbohydrates (WSC) and crude protein (CP) and WSC/CP ratio. AberMagic AR1 and Expo AR1 forage were collected in December 2016, March, June, September and November 2017 and either oven-dried at 60 °C for 48 h (OD_60), at 80 °C for 16 h (OD_80), frozen at −80 °C for 48 h then freeze-dried (−80_FD), or flash-frozen with liquid N then freeze-dried (LN_FD). Data were analyzed by ANOVA in a factorial design with cultivar and drying method as factors. AberMagic AR1 had between 9.0 to 31.5% higher WSC concentration than Expo AR1 in the four samplings. Freeze-drying preserved more WSC than oven-drying treatments (+22.7%), particularly in June. The CP concentration of Expo AR1 was higher only in December (+6.8%), and was 22.9 and 10.9% higher in OD_60 samples compared to LN_FD samples in December and November, respectively. The WSC/CP ratio varied in June, being greater in AberMagic AR1 (+36.1%). Drying method affected WSC/CP ratio in December, June and November where freeze-drying produced greater ratios. Drying techniques generated differences in WSC, CP and WSC/CP ratio, which may affect the accuracy of the estimated impacts of forages on productivity and N use efficiency.
Summer turnips (Brassica rapa L.) have become one of the main supplementary crops in ruminant livestock systems in southern Chile because of accelerated forage growth as well as greater forage yield and nutritive value in the dry season. This study investigated the effects of forage turnip supplementation on the physicochemical and sensory quality of beef from steers. Twenty-seven Holstein–Friesian steers were allocated to one of three dietary treatments: pasture plus concentrate (Control), 50% turnip with a basal diet of pasture hay and rolled corn (T50), and 70% turnip with the same basal diet (T70). Carcass yields and physicochemical and sensory beef attributes, including fatty acid composition of intramuscular fat (IMF) in lean tissue, were measured. Compared to the Control diet, finishing steers on 50% or 70% turnips increased meat redness (a* > 25.9 vs. 22.9 in Control), IMF (1.79% in T50 vs. 1.12% in Control), polyunsaturated fatty acids (PUFAs) (especially n-3), cholesterol, and specific minerals (sodium, manganese and iron); this resulted in a reduction in the subcutaneous fat thickness (0.29 cm in T50, 0.25 cm in T70 vs. 0.51 cm in Control) and shear force of cooked meat (p < 0.05). However, no differences were found between diets in beef juiciness, flavor, and tenderness assessed by trained panelists (p > 0.05). Increasing forage turnip inclusion to 70% resulted in similar beef quality to the 50% inclusion level. Foraged turnips present a promising strategy for producing high-quality beef during periods of limited pasture growth.
19 October 2017 in Crop, Forage & Turfgrass Management