Aggressiveness, nervousness, flightiness, gregariousness and overall disposition were evaluated in F2 Nellore-Angus embryo transfer calves (n = 443) from 13 full sib families and in half Bos indicus, half Bos taurus natural service calves (n = 259) from 4 paternal half sib families. Calves were born from 2003 to 2007, and evaluated shortly after weaning. Steers were evaluated shortly before slaughter for all 5 disposition traits and at slaughter for overall disposition. Heifers were evaluated for overall disposition at calving every year. Scores ranged from 1 to 9, with 1 being docile and 9 being unruly, except at calving where scores ranged from 1 to 5. Between sires for overall disposition, calves by 297J were lowest at weaning (2.83), before slaughter (2.84), and at slaughter (2.45) and second lowest in first calf heifers (2.27). Calves by 437J were highest at weaning (4.10), before slaughter (3.54), at slaughter (2.89) and in first calf heifers (3.10). Bulls had the lowest scores at weaning (2.54), although the number was small (n=10); females were the highest (4.01), and steers were intermediate (3.70). All 5 weaning traits were correlated (P < 0.05) with each other (0.73 to 0.96). The correlation of recipient disposition and weaning disposition of the calves was 0.12 (P < 0.05). Aggressiveness was not significantly correlated with other component traits before slaughter but was with overall disposition (0.19, P < 0.05). All other traits were significantly inter-correlated (0.60 to 0.97). Disposition at weaning was correlated with disposition before slaughter (0.43, P < 0.05). Slaughter disposition was correlated with weaning disposition (0.30, P < 0.001) and disposition before slaughter (0.27, P < 0.001). Disposition in first calf heifers was correlated with weaning disposition (0.34, P < 0.001) and disposition in second calf females (0.53, P < 0.0001). The results indicate that both genetics and recipient disposition affect calf disposition at weaning, calves with better dispositions at weaning have better dispositions later in life, and there is sufficient variability within and between these full sib and half sib families for use in QTL analysis for major genes for disposition in Nellore-Angus cross cattle.

Thesis (Ph. D.)--Cornell University, 1920. / "Reprinted from the Journal of heredity ... vol. XIII, no. 4; Washington, D.C., April, 1922."

Thesis (Ph. D.)--University of Florida, 1974. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 108-117).

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This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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Five Angus (Bt) and 5 Brahman steers (Bi) fitted with ruminal and duodenal cannulas were used in concurrent 5 × 5 Latin squares to determine the effects of supplemental protein degradability and level of supplemental N on utilization of rice straw. Treatments consisted of a control (CON; no supplement) and two levels (50 and 100 mg N/kg BW) of an isonitrogenous supplement (27% CP), either high (H; 72%) or low (L; 28%) in DIP. Forage OM intake (FOMI) was greater for Bt than Bi (P = 0.05). Supplementation increased FOMI in both Bt and Bi (P < 0.05). Organic matter digestibility (OMD) was greater in Bi than Bt (P < 0.01). Supplementation increased OMD for Bi (P = 0.02) but not Bt. Total digestible OM intake (TDOMI) was similar between subspecies (P = 0.12). Bos indicus had greater ruminal NH3-N than Bt (P < 0.01). Plasma urea nitrogen (PUN) was greater for Bi than Bt (P < 0.01) for all treatments and at both 0 and 4 h after feeding. Supplementation tended (P = 0.06) to increase PUN versus CON in Bt, but not Bi (P = 0.82). Bos taurus had numerically (P = 0.19) greater total volatile fatty acids (VFA) across treatments than Bi. Total N intake increased versus CON (P < 0.01), and greater amounts of supplemental N increased total N intake within both subspecies (P < 0.01). Fecal N excretion was greater in Bt than Bi (P = 0.01). Supplementation increased (P < 0.01) fecal N versus CON for both subspecies. Urinary N tended to be higher for Bi than Bt (P = 0.10). Supplementation increased (P < 0.05) urinary N for both subspecies. Retained N was greater for Bt over Bi (P = 0.07). While Bt had greater FOMI, increased OMD for Bi with supplementation resulted in similar TDOMI between subspecies. Overall, Bi had higher NH3-N and PUN than Bt; which increased as level and degradability of supplements increased in both subspecies. Increased supplementation raised N excreted and N balance for both subspecies; fecal N was greater in Bt, while urinary N was greater in Bi.