Dairy Day, 2012

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  • ItemOpen Access
    Reinsemination intervals after timed artificial insemination or estrus-detected inseminations
    (Kansas Agricultural Experiment Station and Cooperative Extension Service, 2014-03-14) Stevenson, Jeffrey S.; jss
    The objective was to quantify the reinsemination intervals of lactating dairy cows that were either inseminated at estrus or received a timed AI (TAI) at first service. Cows in Experiment 1 were enrolled in a TAI program before first AI after calving. Cows detected in estrus after 50 days in milk (DIM) were inseminated, whereas the remainder continued in the TAI program and were inseminated as scheduled. Cows in Experiment 2 also were enrolled in a TAI program and were inseminated accordingly at first service after calving. On day 7 after TAI, cows were assigned randomly to receive either saline (control) or 1,000 IU human chorionic gonadotropin (hCG) to induce accessory luteal structures (corpora lutea) in an attempt to improve pregnancy outcome. First-repeat insemination dates were recorded for all cows after the initial AI and grouped as <18 days, 18 to 25 days, or >25 days since first AI. More cows in Experiment 1 that were inseminated at estrus returned to estrus before 25 days than TAI cows and during summer months had shorter average return intervals by 1.7 days. More cows in Experiment 2 that received saline and had no accessory luteal structures also returned to estrus before 25 days than cows receiving hCG. Equal proportions of saline and hCG-treated cows (25%) in Experiment 2 had retained at least one of their original luteal structures until day 28 after TAI, but were not pregnant at day 32. Of those nonpregnant cows that retained luteal structures, average concentrations of pregnancy-specific protein B (BioPRYN test) concentrations were slightly elevated, but failed to retain the embryos to day 32 after AI. Furthermore, progesterone concentrations of these cows that lost their embryos were compromised compared with pregnant cows by day 21 after AI. Regardless of the number of luteal structures after first insemination, 25% were retained up to 28 days after AI, indicating pregnancy had occurred but embryo loss occurred between pregnancy recognition (day 15) and days 28 to 32 after insemination. Cows receiving TAI also had longer reinsemination intervals than cows inseminated at estrus, a phenomenon that is exaggerated during summer heat stress.
  • ItemOpen Access
    Pregnancy per AI after presynchronizing estrous cycles with Presynch-10 or PG-3-g before Ovsynch-56 in four dairy herds of lactating dairy cows
    (Kansas Agricultural Experiment Station and Cooperative Extension Service, 2014-03-14) Stevenson, Jeffrey S.; Pulley, Stephanie Leeann; jss; spulley
    The objective was to determine the effect of 2 presynchronization treatments on first-service pregnancy rate in 4 dairy herds during warm and cool seasons of the year. Cows with ear tags ending with even digits at calving were enrolled in Presynch-10 with 2, 25-mg injections of prostaglandin F2α (i.e., PG-1 and PG-2) 14 days apart. Cows with ear tags ending with odd digits were enrolled in PG-3-G comprising 1, 25-mg injection of PG (Pre-PG) 3 days before 100 μg gonadotropin-releasing hormone (Pre-GnRH), with the Pre-PG injection administered at the same time as PG-2 in the Presynch-10 treatment in the Presynch-10 treatment. Ten days after PG-2 or Pre-PG, all cows were enrolled in a timed artificial insemination (TAI) protocol (Ovsynch-56; injection of GnRH 7 days before [GnRH-1] and 56 hours after [GnRH-2] PG with AI 16 to 18 hours after GnRH-2). Median days in milk (DIM) at scheduled TAI were 75 days, which did not differ among herds. Cows detected in estrus before the scheduled TAI were inseminated early (early bred; EB). Pregnancy was diagnosed at days 32 to 38 and at days 60 to 66 after TAI by transrectal ultrasonography or transrectal palpation. Data were analyzed with herd as a random effect and with fixed effects of treatment (EB, Presynch-10, PG-3-G), parity (primiparous vs. multiparous), season (hot [June through September] vs. cool-cold [October through May]), DIM, estrus at TAI (0 vs. 1), and all 2-way interactions with treatment. The pregnancy rate at days 32 to 38 for EB (n = 472), Presynch-10 (n = 1,247), and PG-3-G (n = 1,286) were 31.4, 35.0, and 41.2%, respectively; pregnancy rate at days 60 to 66 was 29.8, 32.2, and 37.3%, respectively. Season significantly influenced pregnancy rate at days 32 to 38 and days 60 to 66, but a treatment by season interaction was not detected. The pregnancy rate for PG-3-G and Presynch-10 treatments did not differ during cool-cold weather (d 32 to 38: 46.8 vs. 44.3%; days 60 to 66: 41.6 vs. 41.1%, respectively), but PG-3-G and Presynch-10 produced a higher pregnancy rate than EB at days 32 to 38. During summer, pregnancy rate in PG-3-G was greater than in Presynch-10 (days 32 to 38: 35.9 vs. 26.7% or days 60 to 66: 33.2 vs. 24.4%, respectively), and pregnancy rate in EB cows did not differ from that of Presynch-10 cows. Although pregnancy loss did not differ for EB, Presynch-10, and PG-3-G treatments (4.0, 6.7, and 9.3%, respectively), pregnancy loss from days 32 to 38 and days 60 to 66 was 2-fold greater in thinner cows (<2.5 vs. ≥2.5; 9.0 vs. 4.4%). We concluded that presynchronizing estrous cycles with PG-3-G produced more pregnancies than inseminating cows at estrus during cooler weather and was superior to Presynch-10 during summer.
  • ItemOpen Access
    Hot topic: new research highlights the need for holistic thinking about transition cows
    (Kansas Agricultural Experiment Station and Cooperative Extension Service, 2014-03-14) Bradford, Barry J.; bbradfor
    In the past, efforts to improve the transition to lactation have focused largely on preventing infections and maximizing energy intake in transition cows, and these issues have generally been treated independently. New models, however, are emerging to explain the development of numerous transition disorders. A combination of insults, including social stress, negative energy balance, heat stress, endotoxin exposure, and oxidative stress may promote inflammation, suppress feed intake, and impair both metabolic and immune function during the transition period. These models suggest that transition cow management must be viewed holistically, because the cow’s environment, nutrition, and immune function interact in many complex ways. Fortunately, a number of practical approaches can be used to improve the overall health of transition cows, which can decrease the cull rate in early lactation and improve both productivity and reproductive success.
  • ItemOpen Access
    Meta-analysis of the effects of dietary sugar on intake and productivity of dairy cattle
    (Kansas Agricultural Experiment Station and Cooperative Extension Service, 2014-03-14) Vargas, C. F.; Reinhardt, Christopher D.; Firkins, J. L.; Bradford, Barry J.; cdr3; bbradfor
    A meta-analysis was performed to determine the possible effects of dietary sugar on feed intake and milk production in lactating dairy cattle. The database used in this analysis included 18 treatment comparisons frozm 10 studies reported from 1985 through 2011. Treatment comparisons were used only if: (1) either sucrose (9 comparisons) or molasses (9 comparisons) replaced corn grain without adding fat; and (2) sugar added by treatment ranged from 2 to 5% of dry matter. First, responses to sucrose and molasses were compared to assess whether these sugar sources could be considered together. Statistical analysis provided no evidence for different responses across sugar sources for dry matter intake (DMI), milk yield, energy-corrected milk (ECM) yield, milk fat content, or milk protein content. Different sugar sources were pooled for the remaining analyses; the combined data showed that adding sugar tended to increase DMI by 0.84 lb/day and milk fat content by 0.085%. No effects were detected for milk yield, ECM yield, or milk protein content. This analysis indicates that adding 2 to 5% dietary sugar may promote small increases in DMI and milk fat content but does not consistently increase ECM yield in lactating dairy cattle.
  • ItemOpen Access
    Sodium salicylate during the first 7 days of lactation affects the entire lactation
    (Kansas Agricultural Experiment Station and Cooperative Extension Service, 2014-03-14) Farney, Jaymelynn K.; Mamedova, Laman; Minton, J. Ernest; Coetzee, J. F.; Hollis, Larry C.; Bradford, Barry J.; orcid.org/0000-0002-9150-169X; jkj; mamedova; lhollis; eminton; bbradfor
    Inflammation has been proposed as a contributor to metabolic disorders in transition dairy cows. The purpose of this experiment was to determine if a non-steroidal anti-inflammatory drug, sodium salicylate (SS), benefits transition cows. At calving, 78 cows [primiparous (1P) n = 39; 2nd lactation (2P) n = 24; ≥3 lactations (3P) n = 15] were assigned alternately to either a control or SS treatment for 7 days and production responses were evaluated through the entire lactation. Treatment was administered via individual water bowls, delivering a mean of 123 ± 5.5 (mean ± standard deviation) grams salicylate per day during the 7 days of treatment. Cows were followed throughout the lactation by monthly milk yield and component testing, and the effects of treatment on the risk of leaving the herd and on normalized 305-day milk, fat, and protein yields were determined by Fisher’s exact test and mixed model analysis, respectively. Treatment influenced both 305-day milk and fat yields differently across parities. Milk yield was increased by 17% in 3P SS cows (4,374 ± 1,549 lb greater for 3P SS cows). Primiparous SS cows tended to produce 2,155 ± 824 lb less 305-day milk than control cows; no differences were detected for 2P cows. Furthermore, 3P SS cows produced 285 ± 50 lb more 305-day milk fat and tended to produce 108 ± 40 lb more 305-day milk protein. No effects were detected in 1P or 2P cows. A treatment by parity interaction was observed for the risk of leaving the herd where 1P cows treated with SS tended to have a greater risk of leaving the herd than controls (30% vs. 6% risk). Treatment did not alter herd retention in 2P or 3P groups, and SS had no effect on the risk of leaving the herd overall. Results indicate that SS has long-term effects on lactation characteristics of aged cows, particularly on fat metabolism, but has potential negative effects for primiparous cows.
  • ItemOpen Access
    Evaluation of yogurt with enhanced cysteine content
    (Kansas Agricultural Experiment Station and Cooperative Extension Service, 2014-03-14) Bala, Soumya; Schmidt, Karen A.; kschmidt
    Amino acids are the building blocks of protein and assist with metabolism in the body. In the human body, the amino acid cysteine can be synthesized from methionine by the enzyme Υ-cystathionase. Because certain human subpopulations such as those prone to cataracts have decreased Υ-cystathionase activity, dietary cysteine may be beneficial. Nutritionally, yogurt mix is one of the best dairy food sources of methionine and cysteine, but the heat treatment used in manufacturing yogurt decreases the dietary availability of cysteine. Last year, it was shown that supplementing yogurt mixes with whey protein isolate (WPI) (>90% protein) and processing yogurt mixes at a lower temperature produced yogurts with increased cysteine. Because the quality or cysteine content of the yogurt during the expected storage life is unknown, this study was conducted to determine if a combination of WPI addition and non-optimal process conditions could produce a yogurt with higher cysteine content and an acceptable shelf life. In this study, control yogurt mixes were made with nonfat dry milk (NDM) and processed at 90oC for 7 minutes, whereas the experimental yogurt mixes were made with NDM and WPI and processed at 70oC for 20 minutes. Both mixes were cooled, inoculated, fermented into yogurt, stored at 4°C, and evaluated periodically over a 60-day period. The experimental yogurts had ~2X more cysteine than the control yogurt; this trend was present throughout storage. After 60 days of storage, the water-holding capacity (WHC) and firmness was greater and the syneresis was less for the experimental yogurt than the control yogurt. These results show that yogurt supplemented with WPI and processed at less optimal conditions may be a good source of the conditional amino acid cysteine during storage.