Feeding Management Systems for Wintering Replacement Heifers

Wintering replacement heifers under conditions common to the Northern Great Plains can result in lowered reproductive performance if nutritional levels are inadequate. While it is known that heifers bred to calve at three years of age have less calving and rebreeding problems, economics of modem beef cattle production demand that heifers be bred to calve at two years of age. Timing becomes a very important factor because heifers must cycle and conceive at 15 months or earlier if they are expected to calve as two year olds. Attaining a high percentage of pregnancies by 15 months or sooner hinges directly upon the onset of the first ovulatory estrus in heifers, which has been shown to be quite variable. Numerous studies with heifers have shown that the interaction between heifer breed type and variations in winter energy level during the growing period can significantly alter the age at which heifers reach puberty

System for Feeding Early Weaned Beef Calves

The purpose of this paper was to compare calf rations suitable for an early weaned calf program that have been either commercially prepared or formulated from home grown ingredients

A Comparison of Barley Distillers Dried Grain, Sunflower Oil Meal and Soybean Oil Meal As Protein Supplements in Backgrounding Rations

The focus of this article is to evaluate the capabilities of SFOM and BDDG as replacement protein supplements when compared SBOM in heifer backgrounding rations and to document the economics of feeding each supplement type. The feeding of protein by-products to backgrounded heifer calves on a pound of protein basis resulted in nearly equal gains among heifers fed either SBOM, BDDB or SFOM

Prevalence and antimicrobial resistance of salmonella enterica shed from range and feedlot cattle from post-weaning to slaughter

The objectives of this study were to (1) estimate the prevalence of Salmonella in beef cows and steers at postweaning, finishing and slaughter, and (2) determine antimicrobial resistance of isolates, and (3) assess the association between resistance and presence of class 1 integrons. Fecal samples were collected from 48 cows and 48 steers at multiple sampling periods, and mid-line sponge samples collected from steer hides before slaughter. Bacteriological culture, antimicrobial resistance tests, and polymerase chain reaction testing were performed. Salmonella prevalence varied from 8% (3/38) to 92% (35/38] in cows and from 28% (13/47) to 100% (24/24) in steers, with higher estimates at postweaning than at finishing and slaughter. Of the 200 isolates recovered, the majority (56%) were resistant to 2 or more antimicrobials. Class 1 integrons were detected in 98 isolates, of which 88 (90%) carried the conserved sequence for aadA resistance gene encoding for streptomycin/spectinomycin resistance. Study findings revealed that most steers shed Salmonella at postweaning, indicating widespread exposure either before or after weaning. The recovery of multidrug resistant isolates and presence of class 1 integrons carrying the aadA resistance gene further underscores the dilemma and public health significance associated with veterinary use of antibiotics such as streptomycin in beef cattle. Copyright © 2015, International Association for Food Protection 6200 Aurora Ave., Suite 200W, Des Moines, IA 50322-2864

Effect of Heifer Frame Score on Growth, Fertility, and Economics

A non-traditional forage-based protocol was employed to evaluate replacement heifer growth, fertility, and economics between small frame (SF, 3.50; n = 50) and large frame (LF, 5.56; n = 50) heifers using three increasing gain growth phases. Preceding an 85 d growing-breeding period (Phase 3; P3) the heifers were managed as a common group for Phases 1 and 2 (P1 and P2). During P1, heifers grazed common fields of unharvested corn and corn residue (total digestible nutrients [TDN] 56%) with supplemental hay. For P2, heifers grazed early spring crested wheatgrass pasture (CWG; TDN 62%) that was followed by the final P3 drylot growing and breeding period (TDN 68%). Small frame heifers were lighter at the end of P1 in May and at the start of P3 breeding in August (p = 0.0002). Percent of mature body weight (BW) at the end of P1 (209 d) was 48.7% and 46.8%, respectively, for the SF and LF heifers and the percent pubertal was lower for SF than for LF heifers (18.0% vs 40.0%; p = 0.02). At breeding initiation (P3), the percentage of mature BW was 57.8 and 57.2 and the percentage pubertal was 90.0 and 96.0 (p = 0.07) for the SF and LF heifers, respectively; a 5-fold increase for SF heifers. Breeding cycle pregnancy on days 21, 42, and 63, and total percent pregnant did not differ (p>0.10). In drylot, SF heifer dry matter intake (DMI) was 20.1% less (p = 0.001) and feed cost/d was 20.3% lower (p = 0.001), but feed cost/kg of gain did not differ between SF and LF heifers (p = 0.41). Economically important live animal measurements for muscling were measured in May and at the end of the study in October. SF heifers had greater L. dorsi muscle area per unit of BW than LF heifers (p = 0.03). Small frame heifer value was lower at weaning (p = 0.005) and the non-pregnant ending heifer value was lower for SF heifers than for the LF heifers (p = 0.005). However, the total development cost was lower for SF heifers (p = 0.001) and the net cost per pregnant heifer, after accounting for the sale of non-pregnant heifers, was lower for SF heifers (p = 0.004). These data suggest that high breeding efficiency can be attained among March-April born SF and LF virgin heifers when transitioned to a more favorable May-June calving period through the strategic use of grazed and harvested forages resulting in a lower net cost per pregnant SF heifer

Isolation and characterization of shiga toxin-producing escherichia coli serogroups O26, O45, O103, O111, O113, O121, O145, and O157 shed from range and feedlot cattle from postweaning to slaughter

Cattle are the main reservoirs for Shiga toxin-producing Escherichia coli (STEC) strains. E. coli O26, O45, O103, O111, O121, O145, and O157 are among the STEC serogroups that cause severe foodborne illness and have been declared as adulterants by the U.S. Department of Agriculture, Food Safety and Inspection Service. The objectives of this study were (i) to estimate the prevalence of non-O157 STEC and E. coli O157 in naturally infected beef cows and in steer calves at postweaning, during finishing, and at slaughter and (ii) to test non-O157 STEC isolates for the presence of virulence genes stx1, stx2, eaeA, and ehlyA. Samples were collected from study animals during multiple sampling periods and included fecal grabs, rectal swabs, and midline sponge samples. Laboratory culture, PCR, and multiplex PCR were performed to recover and identify E. coli and the virulence genes. The prevalence of non-O157 STEC (serogroups O26, O45, O103, O111, O121, O113, and O145) fecal shedding ranged from 8% (4 of 48 samples) to 39% (15 of 38 samples) in cows and 2% (1 of 47 samples) to 38% (9 of 24 samples) in steer calves. The prevalence of E. coli O157 fecal shedding ranged from 0% (0 of 38 samples) to 52% (25 of 48 samples) in cows and 2% (1 of 47 samples) to 31% (15 of 48 samples) in steer calves. In steer calves, the prevalence of non-O157 STEC and E. coli O157 was highest at postweaning, at 16% (15 of 96 samples) and 23% (22 of 96 samples), respectively. Among the 208 non- O157 STEC isolates, 79% (164 isolates) had stx1, 79% (165 isolates) had stx2, and 58% (121 isolates) had both stx1 and stx2 genes. The percentage of non-O157 STEC isolates encoding the eaeA gene was low; of the 165 isolates tested, 8 (5%) were positive for eaeA and 135 (82%) were positive for ehlyA. Findings from this study provide further evidence of non-O157 STEC shedding in beef cows and steer calves particularly at the stage of postweaning and before entry into the feedlot

Estrus synchronization of replacement beef heifers by using GnRH, prostaglandin F2α (PGF), and progesterone (CIDR): a multi-location study

Our objectives were to determine whether a fixed-timed artificial insemination (TAI) protocol could yield similar fertility rates to a protocol requiring detection of estrus and whether an injection of gonadotropin hormone-releasing hormone (GnRH) at CIDR (vaginal insert containing progesterone) insertion enhances pregnancy rates. Replacement beef heifers (n=2,077) from 12 locations were assigned randomly to each of four estrussynchronization protocols. All heifers received a CIDR for 7 days, and an injection of prostaglandin F2α (PGF) on the day of CIDR removal. For treatment EAI, heifers were observed for estrus for 84 hours after PGF administration and were inseminated 6 to 12 hours after observed estrus. Any heifer not detected in estrus was injected with GnRH, followed by TAI. For treatment GnRH+EAI, heifers were treated as those for EAI, but also received GnRH at the time of CIDR insertion. For treatment TAI, heifers received a single TAI at 60 hours after PGF administration. For treatment GnRH+TAI, heifers were treated as those for TAI, but also received GnRH at CIDR insertion. The percentage of heifers cycling at the initiation of estrus-synchronization was 91%; the percentage of cycling heifers among locations ranged from 78 to 100%. Overall pregnancy rates among locations ranged from 38 to 74%. Pregnancy rates were 57.3, 54.5, 53.1, and 49.1% for GnRH+EAI, EAI, GnRH+TAI, and TAI, respectively. Although no statistically significant differences in pregnancy rates among treatments were observed, the GnRH+EAI treatment achieved the numerically greatest pregnancy rates. In addition, the GnRH+TAI protocol provides an alternative that allows producers to synchronize heifers without detection of estrus

A Two-Year Study of Vaccination in the Prevention of Bovine E. Coli Diarrhea

This is a discussion of a two year study on vaccination in the prevention of bovine E. Coli Diarrhea. Investigations have demonstrated many causes of diarrhea in calves, including management and infectious agents (34, 73). The infectious agents presently recognized as the causative agents of diarrhea include many viruses such as rotavirus, IBR and BVD. In addition, bacteria including the Salmonella spp., Clostridium spp., and Escherichia coli (E. coli) have frequently been associated with calf diarrhea (84)