Effect of Supplementation during the Breeding Season on a May-calving Herd in the Nebraska Sandhills

Females in their first and second breeding season received either a 32% crude protein (DM) supplement or no supplement throughout the breeding season. Supplementation did not affect heifer BW, BCS, and pregnancy rate at pregnancy diagnosis. Supplementation impacted primiparous cow BW and BCS at pregnancy diagnosis, but did not affect pregnancy rates. Calf birth weight and dystocia rates were unaffected by supplementation for both heifers and primiparous cow. Calves nursing supplemented dams were heavier at weaning. Greater supplementation may be needed to affect pregnancy rate

Comparison of Two Alternate Prostaglandin Products in Yearling Beef Heifers

Yearling heifers were administered 1 of 2 alternate prostaglandin products (Lutalyse vs. Lutalyse HighCon), which differ in concentration of active ingredient and administration route. Timing of estrus, pregnancy rate to AI, and final pregnancy rate did not differ between treatments. Body weight and ADG were also not affected by prostaglandin treatment. These results indicate producers can utilize Lutalyse HighCon, administered subcutaneously (s.c.), to avoid injection site blemishes and reduce carcass discounts with no impact on estrus synchronization or pregnancy rates

Heifer development systems: Dry-lot feeding compared with grazing dormant winter forage

Two hundred ninety-nine Angusbased, nulliparous heifers (253 ± 2 kg initial BW) from 3 production years were utilized to compare traditional postweaning dry lot (DL) development with a more extensive winter grazing system utilizing a combination of corn residue and winter range (EXT). Heifers developed in the DL were offered a common diet after the weaning period for 208 d in yr 1, 194 d in yr 2, and 150 d in yr 3 until breeding. Heifers developed in EXT grazed corn residue for 135 d in yr 1, 106 d in yr 2, and 91 d in yr 3, and then fed in the DL until breeding (yr 1) or grazed dormant winter grass for approximately 60 d before being fed in the DL (yr 2 and 3). All 3 years, heifers were estrus synchronized, with timed AI performed in yr 1. In yr 2 and 3, estrus was detected and those detected in estrus were artificially inseminated approximately 12 h later. Heifers were exposed to bulls 10 d after the last AI for 60 d while grazing summer pasture. During the winter grazing period, EXT heifers gained less (P = 0.01) BW than DL heifers and EXT heifers had lighter (P = 0.02) BW at breeding. Fewer (P \u3c 0.01) EXT heifers reached puberty before breeding. Conception to AI was not different (P = 0.23); however, AI pregnancy rate tended (P = 0.08) to be less in EXT heifers. Final pregnancy rates were not different (P = 0.38) between treatment groups. Although EXT heifers had lighter (P = 0.02) BW at pregnancy diagnosis; however, they did compensate with greater (P = 0.05) ADG after breeding, resulting in similar (P = 0.22) precalving BW. Winter development system did not influence (P \u3e 0.10) percentage of calving in the first 21 d, calf birth date, and calf birth BW, or dystocia score. Pregnancy rate after the second breeding season was not different (P = 0.56) between treatments. Heifer development using extended winter grazing reduced (P \u3c 0.01) the cost of producing a pregnant heifer by $45 compared with DL

Developing Replacement Heifers: Recent Research Findings on Target Weights and Fat Supplementation

Proper development of replacement heifers is critical. Heifers should be managed to reach puberty early, conceive early in the first breeding season, calve unassisted, and breed back early for their second calf. This development needs to be accomplished at low costs without sacrificing performance. Previous studies (Patterson et al., 1992) indicate puberty can be expected to occur at a genetically predetermined size among individual animals; and only when heifers reach predetermined target weights can high pregnancy rates be obtained. Recommended guidelines generally have been 60 to 66% of mature weight in beef heifers, depending on frame size (Patterson et al., 1992). Some studies do not support a critical body weight or composition hypothesis in heifer development (Brooks et al., 1985). Inconclusive results not only exist regarding the appropriate target weight, but also the appropriate time heifers should be placed with bulls in relation to the mature cowherd. Common practice is to breed heifers before the cowherd so they have a longer rebreeding period. This development program requires additional resources if heifers are developed to the same target weight, because an accelerated rate of gain is needed to reach the target weight earlier. As summer calving has gained interest in Nebraska, heifer development programs that allow heifers to conceive early as yearlings and rebreed for a second calf at the lowest cost possible are needed. The objectives of this study were: 1) to compare development of spring-born heifers at two prebreeding target weights (55% or 60% of mature weight) and determine effects on reproduction and cow and calf productivity, and 2) to develop summer-born heifers to similar target weights, but different breeding dates (30 days before or same date as mature cowherd) and determine effects on reproduction and subsequent cow and calf productivity

Heifer development systems: Dry-lot feeding compared with grazing dormant winter forage

Two hundred ninety-nine Angusbased, nulliparous heifers (253 ± 2 kg initial BW) from 3 production years were utilized to compare traditional postweaning dry lot (DL) development with a more extensive winter grazing system utilizing a combination of corn residue and winter range (EXT). Heifers developed in the DL were offered a common diet after the weaning period for 208 d in yr 1, 194 d in yr 2, and 150 d in yr 3 until breeding. Heifers developed in EXT grazed corn residue for 135 d in yr 1, 106 d in yr 2, and 91 d in yr 3, and then fed in the DL until breeding (yr 1) or grazed dormant winter grass for approximately 60 d before being fed in the DL (yr 2 and 3). All 3 years, heifers were estrus synchronized, with timed AI performed in yr 1. In yr 2 and 3, estrus was detected and those detected in estrus were artificially inseminated approximately 12 h later. Heifers were exposed to bulls 10 d after the last AI for 60 d while grazing summer pasture. During the winter grazing period, EXT heifers gained less (P = 0.01) BW than DL heifers and EXT heifers had lighter (P = 0.02) BW at breeding. Fewer (P \u3c 0.01) EXT heifers reached puberty before breeding. Conception to AI was not different (P = 0.23); however, AI pregnancy rate tended (P = 0.08) to be less in EXT heifers. Final pregnancy rates were not different (P = 0.38) between treatment groups. Although EXT heifers had lighter (P = 0.02) BW at pregnancy diagnosis; however, they did compensate with greater (P = 0.05) ADG after breeding, resulting in similar (P = 0.22) precalving BW. Winter development system did not influence (P \u3e 0.10) percentage of calving in the first 21 d, calf birth date, and calf birth BW, or dystocia score. Pregnancy rate after the second breeding season was not different (P = 0.56) between treatments. Heifer development using extended winter grazing reduced (P \u3c 0.01) the cost of producing a pregnant heifer by $45 compared with DL

Field Evaluations of Insecticide Modes of Action Classes for Control of Horn Flies in Nebraska

Insecticides of different Mode of Action (MoA) classes were tested for their ability to reduce horn fly populations on cattle in Nebraska pastures between 2009 and 2016. Macrocyclic lactone products were the most efficacious, reducing horn fly numbers by an average of 93% over ten location years of testing. Organophosphate and pyrethroid MoA products, tested in 7 and 12 location years, reduced fly numbers by 75% and 73%. Classes tested only once were METI (88% reduction) and a combination of organophosphate + pyrethroid (64%)

Developmental and reproductive characteristics of beef heifers classified by number of estrous cycles experienced by start of first breeding

A retrospective analysis was conducted to evaluate the effect of number of estrous cycles exhibited before breeding on growth and reproductive performance of replacement beef heifers fed ad-libitum or restricted by 20% less than ad-libitum during postweaning development over a 9-yr period. Progesterone concentration in blood samples collected at 9- to 11-d intervals were used to assign heifers into groups by number of estrous cycles exhibited before the start of breeding: 0 (nonpubertal; n = 395), 1 (n = 205), 2 (n = 211), 3 (n = 116), or \u3e3 (n = 249). Heifers (P \u3c 0.01) in the 0 cycle group were born 6 d later than the 1, 2, or 3 cycle groups, which were born 4 d later (P \u3c 0.01) than the \u3e3 cycle group. Weight of heifers at birth decreased (P \u3c 0.05) as the number of cycles increased. Weaning weight and ultrasound measures of loin area and fat thickness over the loin at 1 yr age increased as the number of cycles increased (P \u3c 0.01). Postwean weight gain, hip height at 1 yr age, and weights from the start of breeding through precalving increased with cycle numbers in a quadratic fashion (P \u3c 0.02) and were greater (P \u3c 0.05) in ad-libitum than restricted-fed heifers. Pregnancy rate in the 0 cycle group was lower (84%; P \u3c 0.05) than the 1 (90%) or \u3e3 (94%) estrous cycles groups and tended to differ (P \u3c 0.1) from the 2 (88%) and 3 (89%) estrous cycle groups. Interval from the start of breeding to calving was 3 to 5 d longer (P \u3c 0.05) for the 0 cycle group (300 ± 1 d) than other groups. Proportion of heifers calving in the first 21 d was less (P \u3c 0.05) in the 0 or 1 cycle groups than other groups. Pregnancy rates of 2-yr-old cows (n = 898) were lowest (P \u3c 0.05) for the 0 (73%) and 2 (79%) estrous cycle groups than the 1 (85%), 3 (90%), or \u3e3 (92%) estrous cycle groups. Restricted level of feeding during postweaning development resulted in greater (P \u3c 0.05) proportion of heifers in 0 cycle group and lower (P \u3c 0.05) proportion in \u3e3 cycle group, but reproductive performance was not influenced (P \u3e 0.1) by level of feeding or interaction of feeding and estrous cycle grouping. In summary, date of birth and rate of physical maturation (weight, height, and fat deposition) were associated with timing of puberty. Pregnancy rate was greater in heifers that exhibited estrus before the start of breeding, but did not improve from having more than one estrous cycle. Proportion conceiving early was greater for heifers having two or more cycles before breeding

Extending Grazing In Heifer Development Systems Decreases Cost Without Compromising Production

Three experiments compared heifer development systems. In Exp. 1, 299 heifers (253 ± 2 kg) from 3 yr were used to compare dry lot (DL) to grazing corn residue (CR) post weaning. Heifers in the DL consumed a common diet after weaning for 187 d until breeding. The CR heifers grazed for 145 d with a supplement (0.45 kg/d; 28% CP) and were then fed in the DL until breeding. In Exp. 2, 270 heifers (225 ± 2 kg) in 3 yr grazed Sandhills winter range (WR) or CR with a supplement (0.45 kg/d; 28% CP) post weaning. In Exp. 3, 180 heifers (262 ± 3 kg) in 2 yr grazed Eastern Nebraska WR or CR with a supplement (0.45 – 0.90 kg/d; 29% CP) post weaning. The CR heifers had lower (P \u3c 0.001) ADG before breeding compared to DL or WR heifers in Exp. 1 and 2, but WR and CR were similar (P = 0.66) in Exp. 3. The DL and WR heifers were heavier (P \u3c 0.003) than CR at breeding and pregnancy diagnosis in Exp. 1 and 2, but similar (P = 0.62) in Exp. 3. The percentage of heifers pubertal at breeding was greater (P \u3c 0.001) for DL than CR in Exp. 1, for WR than CR in yr 1 and 2 of Exp. 2 (P \u3c 0.01), but similar (P = 0.36) in Exp. 3. Pregnancy rate to AI was lower (P = 0.08) for CR than DL heifers in Exp. 1, but not different (P = 0.89) in Exp. 3. Final pregnancy rate was not affected (P ≥ 0.27) in Exp. 1, 2 or 3. In Exp. 2,, yr 2, CR heifers required (P = 0.01) more calving assistance than WR. Milk production of WR heifers was greater (P = 0.04) than CR in Exp. 3. Calf weaning BW, two-year old AI (Exp. 1 and 3) and final pregnancy rates (Exp. 1, 2 and 3) were not different (P \u3e 0.10). Development grazing CR reduced cost by $45/pregnancy compared to DL, but cost of WR was similar to CR. Development grazing CR reduces ADG before breeding without sacrificing final pregnancy rate. Development grazing WR increases milk production, but does not increase weaning BW. Grazing CR during heifer development reduces cost compared to DL. Grazing CR or WR is suitable for heifer development at similar cost

EC07-281 Body Condition Scoring Beef Cows: A Tool for Managing the Nutrition Program for Beef Herds

This 2007 Extension Circular describes the nine-point body condition scoring system, relationship between body condition and the productivity of the cow herd, and the use of body condition as a management tool to develop and monitor nutritional programs. Using body condition scoring as a management tool can increase the profit potential of the cow/calf enterprise

Effect of Injectable Trace Mineral on Reproductive Performance in Beef Heifers

Trace minerals serve an essential role in regulating reproduction. Free-choice trace mineral supplementation is often provided to grazing beef cattle. An injectable trace-mineral solution used with free-choice trace minerals may be beneficial before breeding to improve mineral status. Therefore, Red Angus-based, May-born heifers were utilized to determine the effects of an injectable trace mineral on reproductive performance. Pregnancy rates did not differ between heifers injected with a trace mineral and heifers that received no injection. Injectable trace mineral at CIDR insertion 33 d before artificial insemination did not influence reproductive performance in heifers with adequate trace mineral status