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'Giant' (Reg. no. CV‐348, PI 701902) is a southern root‐knot nematode (Meloidgyne incognita race 3 and race 4)–resistant forage cowpea [Vigna unguiculata (L.) Walp.] developed by Texas A&M AgriLife Research at Overton, TX. Giant is intended for use as a warm‐season cover crop, a forage and hay crop, and supplemental browse for white‐tailed deer. Giant is an indeterminate, forage type cowpea that produces biomass from May through September in northeast Texas but also flowers 25 days earlier than 'Iron & Clay' cowpea, allowing seed production in northeast Texas before the first average frost date. Single nucleotide polymorphism analysis confirmed the variety mix Iron & Clay as the parental source population for Giant. Forage production of Giant at Overton, TX, in 2019 and 2020 was 5.3 and 6.0 Mg dry matter (DM) ha−1, respectively. Forage production of Giant in 2019 at Prairie and Starkville, MS, was 2.8 and 2.9 Mg DM ha−1, respectively. Protein content of Giant in 2019 at Prairie and Starkville was 21.1 and 21.2%, respectively. Forage production of Giant in 2019 at Chillicothe, TX and Lockett, TX, was 2.6 and 3.6 Mg DM ha−1, respectively. Top growth nitrogen (N) yield of Giant in 2019 at Chillicothe, TX, and Lockett, TX, was 67 and 65 kg N ha−1, respectively. Based on very low nematode reproduction, Giant is rated resistant and partially resistant to southern root‐knot nematode race 3 and race 4, respectively. Core Ideas: Improved cultivars of forage cowpea are needed.Giant forage cowpea produces seed earlier than Iron & Clay cowpea.Giant forage cowpea is resistant to southern root‐knot nematode. [ABSTRACT FROM AUTHOR]

'Ace' (Reg. no. CV‐329, PI 691530) is a small‐seeded cultivar of forage cowpea [Vigna unguiculata (L.) Walp.] that was developed by Texas A&M AgriLife Research at Overton, TX. Ace is intended for use in wildlife supplemental plantings, cover cropping systems, and hay production systems. Forage cowpeas are widely used in Texas and the U.S. southern region as supplemental plantings for white‐tailed deer, but seed production of late‐flowering forage cowpeas is restricted in northern Texas due to freeze kill prior to seed maturity. Mass selection within two highly variable plant introduction lines was used to develop Ace. Seed from five plants with very similar phenotypes, including first bloom in late August, was bulked and tested as experimental forage cowpea. Biomass production of Ace (experimental designation TX‐3) at Overton was 2.8 and 4.7 Mg ha−1 in 2013 and 2015, respectively. Biomass production of Ace at Vernon, TX, in 2015, 2016, and 2017 was 3.9, 5.9, and 6.7 Mg dry matter ha−1, respectively. Protein content of Ace biomass at Vernon in 2015 and 2016 was 16.5 and 16.4, respectively. Seed production of Ace at Vernon ranged from 106 to 670 kg ha−1. The seed size of Ace, expressed as seed weight, was 5.1 g 100 seeds−1, compared with Iron & Clay at 10.6 g 100 seeds−1. Average days to first bloom at Overton for Ace and Iron & Clay are 87 and 114, respectively. Root galling of Ace by southern root‐knot nematode (Meloidgyne incognita Race 3) is very low, and nematode reproduction is low, relative to southern root‐knot nematode–susceptible cowpea lines. Greenhouse seed germination studies indicate about 25% of Ace seed would survive after 2 mo of simulated field conditions and that all seed would be germinated after 3 mo. The reseeding potential of Ace needs further study. [ABSTRACT FROM AUTHOR]

The objectives of the current study were to determine the variation structure within a day and across days when determining dry matter intake (DMI) of Coastal bermudagrass (Cynodon dactylon (L.) Pers.) pasture using dotriacontane (C32) as an external marker, to determine the optimal times for faecal collection for forage DMI estimation and to compare C31 and C33 as internal markers in estimating forage DMI in Brahman bulls. Sixteen Brahman bulls were allocated by weight to four pastures, and stocked at a moderate to low grazing pressure for 63 days from late June to the end of August. Three intake measurement periods (P1, P2, P3) were used; each period consisting of 10 days of twice daily C32 (400 mg/day) administration. Faecal collections were taken during the last 5 days (07.00, 11.00, 15.00 and 19.00 h). The C32 was individually hand fed using Calan gates, with maize gluten as a carrier for the alkane. Gas chromatography was used to determine n-alkanes in the forage and faecal samples. The concentration of C31 was less than C33 in the bermudagrass for all periods (P < 0·001), but the concentration of C31 and C33 in faeces was not significantly different (P > 0·05). The average concentration of C32 in the forage was 5·1, 7·6 and 9·6 mg/kg dry matter (DM), for P1, P2 and P3, respectively, with an average of 7·5 mg/kg DM for all periods. During P1 and P2, the estimation of forage DMI using C33 had a better fit (smaller –2 × log and Akaike's information criterion (AIC)) than using C31 either with or without adjustments for C32. The variation in estimated forage DMI decreased when forage C32 was not included. The variances of forage DMI were similar using C31 across days, but the Pearson correlations between days were low, which suggested that several days of collection were needed to estimate forage DMI accurately. Correlations between collection times within days were medium to high for all periods and varied from 0·65 to 0.97 for C31 and from 0·26 to 0·96 for C33. When all periods were analysed together, estimates of forage DMI either using C31 or C33 had low correlations between days of collection. Adjustment for C32 did not improve the variance and (co)variance matrix. In summary, C33/C32 had the lowest variation in estimating forage DMI, and at least 5 days of faecal collection were needed to decrease the variability of estimating forage DMI. The optimum times for faecal collection were 07.00 and 19.00 h, and it was important to adjust for C32 alkane concentration in estimating forage DMI in Brahman bulls grazing Coastal bermudagrass. [ABSTRACT FROM PUBLISHER]

The objectives of this study were to use the in vitro gas production (IVGP) technique to evaluate the pattern and parameters of anaerobic fermentation of forages from south Texas pastures throughout the year to (i) obtain empirical relationships between the IVGP technique fermentation parameters and chemical composition of the forages and (ii) develop equations to compute total digestible nutrients (TDN). During four consecutive years (2006-2009), forage samples were collected monthly ( n = 39) at the King Ranch, TX, and chemical analyses and IVGP were obtained. For 2006, 2007, 2008 and 2009, the average lag times, h, were 6·47 ± 0·54, 7·75 ± 0·65, 7·49 ± 2·01 and 5·44 ± 1·46, and the average ratio of millilitre of gas per milligram of dry matter was 0·41 ± 0·11, 0·34 ± 0·09, 0·34 ± 0·07 and 0·26 ± 0·10 respectively. There was a moderate negative correlation ( r = −0·53) between lignin and neutral detergent fibre (NDF) and a moderate positive correlation ( r = 0·58) between crude protein and NDF digestibility. The predicted fractional passage rate (kp) by the large ruminant nutrition system model using the level 2 solution was on average 0·0366 h−1. The average computed TDN assuming a kp of 0·04 h−1 was 55·9%. We concluded the IVGP technique may be used to predict TDN values of warm-season forages. [ABSTRACT FROM AUTHOR]

The objective of this study was to characterize residual feed intake (RFI) and to estimate phenotypic and genetic correlations with performance and ultrasound carcass traits in growing heifers. Four postweaning feed efficiency trials were conducted using 468 Brangus heifers. The complete Brangus pedigree file from Camp Cooley Ranch (Franklin, TX), which included 31,215 animals, was used to generate genetic parameter estimates. The heifer progeny from 223 dams were sired by 36 bulls, whereas the complete pedigree file contained 1,710 sires and 8,191 dams. Heifers were individually fed a roughage-based diet (ME = 1.98 Mcal/kg of DM) using Calan gate feeders for 70 d. Heifer BW was recorded weekly and ultrasound measures of 12th- to 13th-rib fat thickness (BF) and LM area (LMA) obtained at d 0 and 70. Residual feed intake (RFIp) was computed as actual minus predicted DM1, with predicted DM1 determined by linear regression of DM1 on mid-test BW0.75 (MBW) and ADG with trial, trial x MBW, and trial x ADG as random effects. Overall means for ADG, DM1, and RFI were 1.01 (SD = 0.15), 9.51 (SD = 1.02), and 0.00 (SD = 0.71) kg/d, respectively. Stepwise regression analysis revealed that inclusion of gain in BF and final LMA into the base model increased the R2 (0.578 vs. 0.534) and accounted for 9% of the variation in DM1 not explained by MBW and ADG (RFIp). Residual feed intake and carcass-adjusted RFI (RFIc) were strongly correlated phenotypically and genetically with DM1 and FCR, but not with ADG or MBW. Gain in BF was phenotypically correlated (P < 0.05) with RFIp (0.22), but not with FCR or RFIc; however, final BF was genetically correlated (P < 0.05) with RFIp (0.36) and RFIc (0.39). Gain in LMA was weakly phenotypically correlated with FCR, but not with RFIp or RFIc; however, gain in LMA was strongly genetically correlated with RFIp (0.55) and RFIc (0.77). The Spearman rank correlation between RFIp and RFIc was high (0.96). These results suggest that adjusting RFI for ultrasound carcass composition traits will facilitate selection phenotypically independent of growth, body size, and carcass composition; however, genetic relationships may still exist between RFI and carcass composition. [ABSTRACT FROM AUTHOR]

Cool-season annuals may fill gaps in seasonal forage availability and reduce stored feed needs for beef cattle producers in the Southeast. These forages can be established during the autumn via sod-seeding or broadcasting on warm-season perennial grass pastures such as bermudagrass and bahiagrass or planted into a prepared seedbed. Opportunity exists to use small grains that vary in their individual growth distribution to extend the grazing season. Small grains adapted to the region include cereal rye (Secale cereale), wheat (Triticum aestivum), oats (Avena sativa), and triticale (x Triticosecale). These species provide bimodal forage dry matter (DM) production during the autumn and early winter months, and can be grown in monocultures or mixtures. Cereal rye generally provides forage DM earliest in the season, followed by triticale, wheat, and oats. Fall production potential of these species is primarily dependent on planting method, seeding date, fertility, and variety selection. These species provide high quality forage DM that may support animal performance in stocker and cow-calf operations with minimal supplementation, and can be grown in combination with annual ryegrass and/or legumes to further lengthen the window of grazing. Annual ryegrass and legumes in the Southeast includes coldtolerant and rust-resistant diploid and tetraploid varieties of ryegrass, and adapted true clover (Trifolium sp.) varieties. Autumn-planted ryegrass and/or clovers including primarily crimson, arrowleaf, ball, and white clover, provide minimum to nonexistent forage mass for grazing during the fall. Naturally reseeding ryegrass or clovers will often provide earlier forage mass; however, DM is usually not adequate for stocking until late-January through May. With appropriate levels of N fertilization, ryegrass produces more forage DM, and thus allows for earlier stocking and greater stocking rates compared to clovers. Tetraploid varieties of ryegrass, when seeded into prepared seedbed, can provide adequate forage mass for fall grazing. Earliness of forage mass for stocking of clover ranges from crimson (earliest), to arrowleaf and ball (mid), to white clover (latest). White clover, however, in adapted soils and with adequate spring-summer rainfall and proper stocking rate, can provide grazing during early to mid-summer months. From the first frost event in late fall through the early spring months, cool-season annual forages provide actively growing forage to extend fall and spring grazing for cow-calf and/or stockers during winter dormancy of perennial grass pastures. [ABSTRACT FROM AUTHOR]

Cool-season annuals may fill gaps in seasonal forage availability and reduce stored feed needs for beef cattle producers in the Southeast. These forages can be established during the autumn via sod-seeding or broadcasting on warm-season perennial grass pastures such as bermudagrass and bahiagrass or planted into a prepared seedbed. Opportunity exists to use small grains that vary in their individual growth distribution to extend the grazing season. Small grains adapted to the region include cereal rye (Secale cereale), wheat (Triticum aestivum), oats (Avena sativa), and triticale (×Triticosecale). These species provide bimodal forage dry matter (DM) production during the autumn and early winter months, and can be grown in monocultures or mixtures. Cereal rye generally provides forage DM earliest in the season, followed by triticale, wheat, and oats. Fall production potential of these species is primarily dependent on planting method, seeding date, fertility, and variety selection. These species provide high quality forage DM that may support animal performance in stocker and cow-calf operations with minimal supplementation, and can be grown in combination with annual ryegrass and/or legumes to further lengthen the window of grazing. Annual ryegrass and legumes in the Southeast includes coldtolerant and rust-resistant diploid and tetraploid varieties of ryegrass, and adapted true clover (Trifolium sp.) varieties. Autumn-planted ryegrass and/or clovers including primarily crimson, arrowleaf, ball, and white clover, provide minimum to nonexistent forage mass for grazing during the fall. Naturally reseeding ryegrass or clovers will often provide earlier forage mass; however, DM is usually not adequate for stocking until late-January through May. With appropriate levels of N fertilization, ryegrass produces more forage DM, and thus allows for earlier stocking and greater stocking rates compared to clovers. Tetraploid varieties of ryegrass, when seeded into prepared seedbed, can provide adequate forage mass for fall grazing. Earliness of forage mass for stocking of clover ranges from crimson (earliest), to arrowleaf and ball (mid), to white clover (latest). White clover, however, in adapted soils and with adequate spring-summer rainfall and proper stocking rate, can provide grazing during early to mid-summer months. From the first frost event in late fall through the early spring months, cool-season annual forages provide actively growing forage to extend fall and spring grazing for cow-calf and/or stockers during winter dormancy of perennial grass pastures. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the effect of residual feed intake (RFI), residual average daily gain (RADG), feed to gain (F:G) on productivity in Brahman heifers (n=242). Following a 56-d post-weaning period for six calf crops, Brahman heifers were individually fed for periods of 60-d at 2.8% of their body weight in a Calan gate system. Rations were adjusted at weekly intervals. For each contemporary group, the mean and standard deviation of RFI, RADG, and F:G was calculated. Based on the mean plus or minus ½ standard deviation for each group, heifers with the lowest RFI and F:G were classified as efficient (E), while higher RFI and F:G heifers were classified as moderately efficient (ME) or inefficient (I). For RADG, heifers with the highest RADG were classified E, while lower RADG heifers were classified as ME or I. Cow records for age at first calving (AFC), interval from the first to second calf (CI) and calf records for birth weight (BW) and 180-d adjusted weaning weight (AWW) were recorded. Data were analyzed using mixed linear models. The additive genetic effects were modeled as random in all analyses. In analyses of calf traits, maternal additive genetic effects were also random effects. For all traits, cow year of birth was investigated as a fixed effect. For calf traits, calving interval, the calf birth year was a fixed effect. Calf breed, season of birth, and sex were fixed effects in analyses of calf traits. The effects of interest were 3-level classification variables created using the upper and lower quartiles and the two middle quartiles combined of RFI, RADG, and FG. These were modeled in distinct analyses. In analyses of RADG, the high (inefficient) and low (efficient) RFI groups of heifers differed (0.03 ± 0.018 and -0.04 ± 0.02, respectively; P=0.03). In analyses of F:G all RADG groups differed (P<0.01) as expected; that is E (8.0 ± 0.25) < ME (9.5 ± 0.24) < I (12.6 ± 0.25; P< 0.01). Heifer AFC and CI were not significantly influenced by efficiency classifications for RFI, RADG, or F:G (P>0.10). As expected, male calves had greater BW (P<0.05). Classification for efficiency group did not influence either BW or AWW. RFI, RADG, or F:G did not affect reproductive or calf performance in young Brahman cows. Selection for RFI will result in selecting against RADG or F:G. [ABSTRACT FROM AUTHOR]

The forage-animal interface is a vital component of agricultural systems that is often overlooked by both agronomy and animal science programs. As such, current grazing models do not always provide a satisfactory understanding of how forage species and/or cultivars respond to livestock interaction in both production and physiology, how forage can influence the animal, and how the nexus of these two entities may affect the environment. The objective of this effort was to develop a conceptual framework of a dynamic model that combined the forage and ruminant livestock interactions, and to provide the initial parameterization of a model for bermudagrass pastures. The systems dynamic methodology was used. The causal loop diagram (CLD) was first envisioned based on the hypothesis that not only can forage factors affect performance and behavior of the grazing animal, but the grazing animal, through its herbivorous behavior and selective intake, can affect and alter the physiology, growth, and performance of the forage and the pasture. Generation of a preliminary stock-and-flow diagram (SFD) with variable flight simulators was also performed. The main CLD was a composite of four sub-models that represented the agronomic, animal, atmospheric, and soil subsystems. The limitations of this model existed in the lack of meta-analytical publications in which necessary equations have been summarized that could be used in model programming. The parameterization of the model suggested that forage allowance was the driving factor in animal ADG, and forage growth rate was governed by a combination of evapotranspiration, defoliation, soil N, and precipitation. Our simulation of the bermudagrass scenario suggested that under these production conditions, most portions of the model operated in a traditional goal-seeking fashion. The initial results provided the documentation of the interface concept for the benefit of forage agronomy and animal nutrition programs as well as the foundation for advancements of the model to eventually serve as potential decision aid in production-economic strategies. [ABSTRACT FROM AUTHOR]

The forage-animal interface is a vital component of agricultural systems that is often overlooked by both agronomy and animal science programs. As such, current grazing models do not always provide a satisfactory understanding of how forage species and/or cultivars respond to livestock interaction in both production and physiology, how forage can influence the animal, and how the nexus of these two entities may affect the environment. The objective of this effort was to develop a conceptual framework of a dynamic model that combined the forage and ruminant livestock interactions, and to provide the initial parameterization of a model for bermudagrass pastures. The systems dynamic methodology was used. The causal loop diagram (CLD) was first envisioned based on the hypothesis that not only can forage factors affect performance and behavior of the grazing animal, but the grazing animal, through its herbivorous behavior and selective intake, can affect and alter the physiology, growth, and performance of the forage and the pasture. Generation of a preliminary stock-and-flow diagram (SFD) with variable flight simulators was also performed. The main CLD was a composite of four sub-models that represented the agronomic, animal, atmospheric, and soil subsystems. The limitations of this model existed in the lack of meta-analytical publications in which necessary equations have been summarized that could be used in model programming. The parameterization of the model suggested that forage allowance was the driving factor in animal ADG, and forage growth rate was governed by a combination of evapotranspiration, defoliation, soil N, and precipitation. Our simulation of the bermudagrass scenario suggested that under these production conditions, most portions of the model operated in a traditional goal-seeking fashion. The initial results provided the documentation of the interface concept for the benefit of forage agronomy and animal nutrition programs as well as the foundation for advancements of the model to eventually serve as potential decision aid in production-economic strategies. [ABSTRACT FROM AUTHOR]