J. A. Hornsby

The Immune Response and Performance of Calves Supplemented with Zinc from an Organic and an Inorganic Source1

Abstract Two experiments were conducted to determine the effects of supplemental zinc (Zn) from an organic and an inorganic source on growth performance, serum Zn concentrations, and immune response of beef calves. Treatments consisted of: i) control (no supplemental Zn), ii) Zn sulfate, or iii) Zn-amino acid complex. Zinc sources were supplemented to provide 360 mg of Zn/d. Experiment 1 was a 28-d study using 84 steers (240 ± 1.5 kg) fed bermudagrass hay (21 mg Zn/kg DM) with 1.8 kg/d of the appropriate corn-based supplement. In Exp. 2, 75 heifers (176 ± 2.5 kg) were fed bermudagrass hay (38 mg Zn/kg DM) and the supplements for 140 d. In Exp. 1, ADG was greater (P 0.10) among treatments for the entire 28-d study. In Exp. 2, there was no effect (P>0.10) on ADG as a result of Zn supplementation. In Exp. 2, Zn-supplemented heifers had a greater response (P=0.06) tophytohemagglutinin 24 h after an intradermal injection. In Exp. 2, calves supplemented with Zn-amino acid complex had a greater antibody response to a second vaccination for bovine respiratory syncytial virus than did control or Zn sulfate-supplemented calves (treatment by day interaction, P=0.06). There was not a consistent benefit of supplemental Zn on growth of calves, but there was a positive impact of supplemental Zn on some immune response measurements.

Supplemental trace minerals (zinc, copper, and manganese) as sulfates, organic amino acid complexes, or hydroxy trace-mineral sources for shipping-stressed calves

ABSTRACT Crossbred calves (n=350; average BW 240±1kg) were obtained from regional livestock auctions. Within each set (block, n=4), calves were stratified by BW and arrival sex into 1 of 8, 0.42-ha pens (10 to 12 calves per pen). Pens were assigned randomly to 1 of 3 treatments consisting of supplemental Zn (360mg/d), Mn (200mg/d), and Cu (125mg/d) from inorganic (zinc sulfate, manganese sulfate, and copper sulfate; n=2 pens per block), organic (zinc amino acid complex, manganese amino acid complex, and copper amino acid complex; Availa-4, Zinpro Corp., Eden Prairie, MN; n=3 pens per block), and hydroxy (IntelliBond Z, IntelliBond C, and IntelliBond M; Micronutrients, Indianapolis, IN; n=3 pens per block) sources. During the 42- to 45-d backgrounding period calves had ad libitum access to bermudagrass hay and were fed corn and dried distillers grain–based supplements that served as carrier for the treatments. After removal of data for chronic (n=6) and deceased (n=1) calves, trace-mineral source had no effect on final or intermediate BW (P=0.86) or ADG (P≥0.24). With all data included in the analysis, dietary treatments had no effect on the number treated once (P=0.93), twice (P=0.71), or 3 times (P=0.53) for bovine respiratory disease or on the number of calves classified as chronic (P=0.55). Based on these results, trace-mineral source had no effect on total BW gain, ADG, or morbidity during the receiving phase in shipping-stressed cattle.

Postpartum Maternal Behavior Score in Six Breed Groups of Beef Cattle over Twenty-Five Years

The objective of this study was to determine the effects of fixed sources of variation on postpartum maternal behavior score (MBS) in six breed groups of beef cows. Postpartum MBS were determined on 5070 births representing the progeny of 142 sires and 145 maternal grandsires used in purebred herds of the University of Arkansas Agricultural Experiment Station over a 25-yr period. Breed groups included Angus (n = 2073), Charolais (n = 549), Hereford (n = 722), Heritage Angus (n = 445), Polled Hereford (n = 981), and Red Poll (n = 300). Within 24 h of birth, a MBS was assigned as the handler obtained calf birth BW and body condition of each calf. Postpartum MBS were 1) very aggressive, 2) very attentive, 3) indifferent, and 4) apathetic. Variation in MBS across breeds was partitioned using a repeated measures model that included terms for an overall mean, year, breed, within breed, age of dam, sex of calf, body condition of calf, sire of calf, and maternal grandsire of calf. Across breed, important sources of variation (P<0.01) in MBS were year, age of dam, body condition of calf at birth, breed, sire within breed, and sire of dam within breed. Dams giving birth to calves in thin body condition had greater (P<0.01) mean MBS than dams giving birth to calves in average or fat body condition (2.34 vs 2.24 vs 2.19), respectively. These results suggest MBS is influenced by several sources of variation, which should be considered when evaluating maternal behavior in selection programs.

Relationships Among Growth Characteristics of Replacement Angus Heifers1

Angus heifers (n = 88) were used over 3 yr to determine the relationship between two sets of traits considered to be indicators of growth. Data were collected at weaning (7 to 8 mo), yearling (10 to 11 mo), andprebreeding (13 to 14 mo) and included BW, hip height (HH), hip width (HW), pelvic height (PH), pelvic width (PW), lactate dehydrogenase (LDH) activity, longissimus area (LA), and backfat thickness (BKFAT). Measurements were grouped into two sets of traits; Set 1 included BW, HH, HW, and LDH activity; Set 2 included PH, PW, LA, and BKFAT. Weight was correlated (P 0.8; P 0.48; P < 0.01) with Set 2 traits at prebreeding. These results suggest that the Set 1 measurements, as early as at weaning, could be used as indicators of Set 2 variables at prebreeding. The canonical coefficients of Set 1 traits were used to rank heifers as either above or below the mean. Ranking heifers based on Set 1 measurements at weaning resulted in a greater (P < 0.01) percentage of heifers calving as 2-yr olds. Correlations between Set 1 and Set 2 traits suggest that external measurements coupled with LDH activity could be used in identifying replacement beef heifers that have larger pelvic dimensions at breeding and a greater frequency of calving as 2-yr olds.