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New Mexico State University (2018)

Weight gain and behavior of Criollo vs crossbred steers developed on Chihuahuan Desert rangeland

Montana McIntosh Matthew

Titre : Weight gain and behavior of Criollo vs crossbred steers developed on Chihuahuan Desert rangeland

Auteur : Montana McIntosh Matthew

Université de soutenance : New Mexico State University

Grade : Master of Science (MS) 2018

Résumé
A challenge associated with raising Raramuri Criollo (RC) cattle for beef is the lack of markets for weaned calves. Ranchers that raise RC cattle must either cross their cows with improved beef breed bulls to obtain marketable calves at weaning or develop their RC yearlings on rangeland. An experiment was conducted in the Chihuahuan Desert using two cohorts of (RC), Corriente (CO) and Criollo x beef-breed crossbreds (XC) to investigate the effects of steer biotype ( breed) on growth performance and landscape utilization. Fifty-seven yearling steers (cohort 1, n = 31 ; cohort 2, n = 26) were weighed every 60 d to determine individual body weight (WT), and average daily gain (ADG). Nine steers per cohort were monitored with Lotek 3300LR GPS collars at 5-min intervals for one month during winter (2015 and 2016) and late summer (2016 and 2017) to compare landscape utilization patterns of RC and XC individuals. WT data were analyzed as repeated measures using mixed procedures of SAS 9.4. Discriminant analyses were conducted to determine whether : 1) RC and XC steers could be discriminated into different groups based on their grazing behavior ; 2) steers could be discriminated into groups based on their winter vs summer grazing behavior patterns ; and 3) steers belonging to cohort 1 and cohort 2 could be discriminated into significantly different groups on the basis of their grazing behavior. PROCS DISCRIM and STEPDISC procedures of SAS 9.4 were used for these analyses. Linear pairwise correlations between behavior variables and either ADG or initial body weight were conducted using PROC CORR in SAS 9.4. All steers reached slaughter weights at 30 months of age using our desert grass-fed protocol. Final live weight of XC was greater than that of RC and CO counterparts (P < 0.01). ADGs were not different by breed (P = 0.06). RC and XC steers exhibited very similar movement and spatial distribution patterns and could not be discriminated into detectably different groups based on their grazing behavior patterns (P = 0.08). RC and XC steers exhibited similar behavior to those previously described in RC cows. Steers were discriminated into statistically different season (P < 0.01) or cohort (P < 0.01) groups based on their grazing behavior patterns. Significant linear pairwise correlations between ADG and eight animal activity variables were detected (P < 0.05) during late summer. Initial steer live weight was significantly correlated with nine animal activity variables in winter (P < 0.05). Our results suggest that XC, RC, and CO steers can be developed to slaughter weights in 30 months using a rangeland-based grass-fed protocol and that RC and XC exhibit the desirable grazing behavior traits previously observed in RC cows.

Présentation (World Cat )

Page publiée le 10 novembre 2018