112 research outputs found
Het gebouw als bewijs
No full textReview of a book edited by Ronald Stenvert and Gabri van Tussenbroe
Influence of Corn Hybrid Traits on Digestibility and the Efficiency of Gain in Feedlot Cattle
No full textTwo experiments were conducted to determine the influence of chemical and physical corn kernel traits on digestibility and feedlot cattle performance. Seven commercially available corn hybrids representing a range in kernel traits were evaluated for a variety of chemical and physical traits that included test weight, 1,000-grain weight, kernel size, starch, CP, amylose, Stenvert Hardness tests (kernel hardness traits), tangential abrasive dehulling device loss, 12-h in vitro starch disappearance, and rate and extent of in situ DM disappearance. Differences among hybrids existed for all physical kernel traits measured. In Exp. 1, 224 steers in 28 pens were fed the same hybrids for 167 d in a completely randomized design. All diets were formulated to have 12.5% CP and contained 66% dry-rolled corn (DM basis). There were no differences (P \u3e 0.20) among corn hybrids for DMI, ADG, or carcass characteristics. However, efficiency of gain (G:F) was influenced by hybrid (P \u3c 0.01) with a difference of 9.5% from the least to the most efficient. In Exp. 2, 7 ruminally cannulated heifers were used in a 7 × 7 Latin square design to determine the effects of these hybrids on nutrient digestibility, VFA concentrations, and ruminal pH. Total-tract OM and starch digestibilities were not different (P \u3e 0.15) among hybrids and averaged 77.9 and 95.1%, respectively. Differences (P \u3c 0.05) among hybrids existed for ruminal propionate concentration and the acetate to propionate ratio. Kernel hardness traits correlated (P \u3c 0.05) with G:F were 1,000- grain weight (r = −0.81), Stenvert time to grind (r = −0.83), and the proportion of Stenvert soft to coarse particle height (r = 0.83). Propionate concentration was not correlated (r = 0.45) with G:F but was correlated (P = 0.02) to the Stenvert time to grind (r = −0.83). Cattle fed dry-rolled corn hybrids with greater proportions of soft endosperm had greater concentrations of propionate and gained more efficiently than cattle fed hybrids with a harder endosperm. Selecting for these softer kernel traits may improve the efficiency of gain in feedlot cattle
Evaluation of endosperm hardness and correlated responses of agronomic traits after four cycles of recurrent selection in two synthetic populations of maize
No full textEvaluation of four cycles of S\sb1 recurrent selection for increased kernel endosperm hardness was conducted at four locations over 2 years in the synthetic maize populations HSyn73 and HSyn99. Endosperm hardness was measured using the Stenvert hardness test and kernel density. Evaluation of progress over cycles of selection was performed on S\sb1 testcross hybrids. Test weight per bushel, grain yield, percent grain moisture, percent stalk lodging, percent seedling emergence, and plant and ear height were also measured to determine possible correlated responses of these agronomic characters to selection for endosperm hardness. Selection for endosperm hardness was performed using visually selected ears for advancement to the next cycle. Visual selection for endosperm hardness may be inadequate to detect small increases in endosperm hardness. The Stenvert hardness test is a quantitative measure which accurately indicates the level of endosperm hardness. Evaluation of progress for increased endosperm hardness was highly significant for the Stenvert hardness test in population HSyn73 only. A positive linear effect for kernel density over cycles was also significant in population HSyn73. Population HSyn99 exhibited no significant response to selection of endosperm hardness. Significant variation was present for random lines within cycles of selection for most agronomic characters in both synthetics, indicating selection progress was still possible. Highly significant phenotypic and genotypic correlations were seen between kernel density and Stenvert hardness measure in HSyn73 (r = 0.681 and r = 0.912, respectively) and in HSyn99 (r = 0.725 and r = 0.959, respectively). Test weight per bushel was significantly correlated with both Stenvert hardness and kernel density for both populations. Grain yield expressed a significant negative phenotypic correlation with both endosperm hardness measures in both populations. Plant and ear height showed significant phenotypic and genotypic correlations in both populations, and also ear height with percent stalk lodging. Plant height was highly correlated with both percent grain moisture and percent stalk lodging in population HSyn73, possibly resulting from late maturing hybrids having tall stature with high ear placement. Selection for kernel endosperm hardness did not alter agronomic performance for most traits measured. However a decrease in grain yield indicates that selection pressure for yield should occur concurrently when selecting for endosperm hardness
Development of a rapid screening method for improved breeder popcorn lines
No full textFor microwaveable popcorn, quality is of great importance. Quality can be improved by developing popcorn breeding lines. However, breeding programs have a small amount of material and need nondestructive analytical methods. The objective was to develop a nondestructive method for selection of breeding material. The following baseline information was determined for 18 popcorn lines: number of kernels per 10g, density, Stenvert hardness, pericarp thickness, moisture loss, and total starch content. Finally, correlations between popping performance and the baseline information were computed. Significant differences were found among samples for popping performance and all sample characteristics. Samples with high expansion volume had generally greater flake sizes, lower number of kernels/10 g, lower kernel density and lower Stenvert hardness values. Pericarp thickness did not appear to be related to popping performance. Moisture loss during microwave heating correlated significantly (r = 0.76) with percentage of unpopped kernels, indicating that the number of unpopped kernels increased as a greater amount of moisture was lost during microwave heating. With regard to total starch content, samples with high expansion volume and large kernel size had the highest starch content. Total starch content had weak but significant correlations with number of kernels/10g (r = -0.64), and flake size (r = 0.59). Number of kernels/10g and flake size were significantly and negatively correlated with each other (r = -0.77). Predictive correlations were not observed between physical and chemical traits and popping performance. It was difficult to find predictive relationships due to the narrow range of the sample traits. Expansion volume was used for developing a model with near-infrared spectroscopy (NIRS). A total of 128 samples were used and models were calibrated with different combinations of the samples. A model calibrated with 84 popcorn samples at equilibrium moisture content (13.5-14%) resulted in a cross validation R 2 = 0.56 and a RMSECV = 2.16. When the model was tested with an analysis of unknown samples, it accurately predicted expansion volume of new samples; especially samples with expansion volume greater than 50 cc/g. However, more work is needed to improve the NIRS model and the accuracy of predicting popcorn expansion volume
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