Comparison of diets collected from esophageally fistulated cows to forage quality estimated from fecal analysis

Differences in forage quality (crude protein and energy) were analyzed between esophageally fistulated diets, analysis of fecal samples with Nutrition Balance Analyzer (NUTBAL) analysis, and analysis of handclipped forage samples. On upland range sites, hand- clipped samples provided forage quality estimates that were closer to esophageally fistulated diets than samples analyzed with the NUTBAL analysis. Aft er one year of data collection, it appears that there may be some inconstancies with the NUTBAL analysis for estimates on rangeland forage quality in the Nebraska Sandhills. More data is needed to verify these results; however, making management supplementations decisions solely on the NUTBAL analysis may not always be accurate on Sandhills rangeland

Impact of Winter Supplementation of May Calving Cows and Heifer Development System in Two Different Breeding Seasons on Subsequent Growth and Reproduction

In Exp. 1, May-calving cows were utilized to evaluate the effects of winter supplementation on heifer progeny. Cows grazed either dormant upland winter range with or without a protein supplement or grazed dormant meadow with or without a protein supplement. In Exp. 2, replacement heifers from March and May calving herds were offered ad libitum meadow hay and 4 lb/d supplement or grazed meadow and offered 1 lb/d supplement from mid-January to mid-April. Calf weaning BW and ADG from birth to weaning was less for calves from cows grazing winter range with no supplement compared with all other dam treatments. Heifer development system did not impact final pregnancy rates. Therefore, a reduced input winter heifer development system is a viable option in both early and late summer breeding seasons. However, winter supplementation of May-calving dams did influence heifer progeny ADG from birth to weaning

Effects of Ingestion and Collection Bag Type on Nutrient Composition of Forage Samples from Esophageally Fistulated Cattle

Ingestion and mastication of forage samples adds ash. Generally, levels of CP were lower and NDF and IVOMD were similar for post-ingested versus pre-ingestedforage. Bag type (screen vs. solid) generally did not affect ash, NDF, or IVOMD. Bag did not affect CP of alfalfabut CP of grass samples from screen bags was lower than solid bags. More fresh than dry forage was recovered through the esophageal opening

Effects of Supplementing Lactating, June-calving Cows on Second-calf Pregnancy Rates

A two year experiment evaluated the influence of supplementation pre-breeding on second-calf pregnancy rates in June-calving heifers. For 60 days before start of the breeding season, heifers were assigned to one of two treatments: supplementation of dried distillers grains (1.5 lb/day) to meet energy and metabolizable protein requirements or unsupplemented control. Supplementation improved body condition score during the supplementation period and resulted in increased body condition score at weaning. In year 1, feeding supplement to the dam did not change calf weight gain but feeding supplement increased calf weight in year 2. Pregnancy rates were 90% and not changed by supplementation

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%)

Urinary Allantoin as an Estimate of Microbial Protein Synthesis

Allantoin excretion in the urine was evaluated as a marker for bacterial protein production in lactating and dry cows grazing Sandhills range and meadows. Allantoin excretion declined with season as diet digestibility declined. Bacterial protein predicted from allantoin was significantly related (R2 = .62) to bacterial protein predicted by NRC. Urinary allantoin has potential as a tool to predict bacterial protein production in grazing cattle

Microbial Protein Synthesis and Efficiency in Nursing Calves

Microbial protein synthesis and efficiency were estimated in springborn nursing calves grazing native range and subirrigated meadow. Forage intake increased from 1.5 lb/ day (0.6% BW) in June to 5.9 lb/day (1.2% BW) in September while milk intake decreased over the same period. Microbial protein (MCP) synthesis increased from 67 g/day in May to 278 g/day right before weaning in September. Urinary allantoin was used as a marker. Efficiency of MCP synthesis was approximately 19% of forage digestible organic matter (OM) intake

Effect of Calving Season and Wintering System on Cow Performance

Four years of data from three different calving seasons and two different cow wintering systems were evaluated utilizing 218 cows/year. Cows calved in spring, summer, or fall and were wintered on native Sandhills range or cornstalks. Calving season affected cow body weight (BW) and body condition score (BCS) throughout the production year; calving in the fall reduced number of calves weaned per cow. No differences were observed between cows wintered on Sandhills range and those wintered on cornstalks

Effects of Prebreeding Body Weight or Progestin Exposure Before Breeding on Beef Heifer Performance Through the Second Breeding Season

Two experiments evaluated prebreeding target BW or progestin exposure for heifers developed lighter than traditional recommendations. Experiment 1 evaluated the effects of the system on heifer performance through subsequent calving and rebreeding over 3 yr. Heifers (229 kg) were assigned randomly to be developed to 55% of mature BW (299 kg) before a 45-d breeding season (intensive, INT; n = 119) or 50% of mature BW (272 kg) before a 60-d breeding season (relaxed, RLX; n = 142). Prebreeding and pregnancy diagnosis BW were greater (P ≤ 0.006) for INT than RLX heifers. Overall pregnancy rate did not differ (88.4%; P = 0.51), but RLX heifers had later calving dates (7 d; P \u3c 0.001) and lighter calf weaning weights (194 ± 4 vs. 199 ± 4 kg; P \u3c 0.07) compared with INT heifers. Calf birth weight, calving difficulty, second-calf conception rates, and 2-yr-old retention rate did not differ (P \u3e 0.15) between systems. Cost per pregnant 2- yr-old cow was less for the RLX than the INT heifer development system. Of heifers that failed to become pregnant, a greater proportion (P = 0.07) of heifers in the RLX than in the INT system were prepubertal when the breeding season began. Therefore, a second 2-yr experiment evaluated melengestrol acetate (MGA, 0.5 mg/d) as a means of hastening puberty in heifers developed to 50% of mature BW. Heifers were assigned randomly to the control (n = 103) or MGA (n = 81) treatment for 14 d and were placed with bulls 13 d later for 45 d. Prebreeding and pregnancy diagnosis BW were similar (280 and 380 kg, respectively; P \u3e 0.10) for heifers in the control and MGA treatments. The proportion of heifers pubertal before breeding (74%), pregnancy rate (90%), calving date, calf weaning weight, and second breeding season pregnancy rate (92%) were similar (P \u3e 0.10) between treatments. Developing heifers to 50 or 55% of mature BW resulted in similar overall pregnancy rates, and supplementing the diets of heifers developed to 50% of mature BW with MGA before breeding did not improve reproductive performance

Effect of Pre-breeding Weight and MGA Supplementation on Heifer Performance

Developing heifers to reach a target weight of 50% of mature body weight at the beginning of the breeding season is an effective method for reducing heifer development cost. Net costs to produce a bred yearling heifer and 2-year-old cow were lower when heifers were developed to 50% rather than 55% of mature body weight, regardless of breeding season length. Administration of oral progestin to heifers developed to 50% mature body weight prior to breeding did not affect reproductive performance during the first breeding season when heifers were exposed to bulls 13 days after the end of progestin treatment