Groups of 9 or 10 cows were assigned to one of three treatments 1) machine-milking three times daily, 2) machine-milking six times daily, and 3) suckling three times daily in addition to machine- milking three times daily. Treatments were conducted during the first 6 wk postpartum; thereafter, all cows were milked three times daily. During treatment, milk production was highest for suckled cows and lowest for cows milked three times daily. The DMI were similar for suckled cows and cows milked three times daily but higher for those milked six times daily. Body weight loss was greatest for suckled cows and least for cows milked three times daily. During wk 7 to 18 postpartum, cows milked six times daily exhibited a carry-over effect on milk production that was greater than that of other groups, During treatment, plasma growth hormone and IGF-I concentrations were elevated for suckled cows and, to a lesser extent, for cows milked six times daily. Prolactin and oxytocin similarly increased, but insulin decreased in suckled cows and, to a lesser extent, in cows milked six times daily. Posttreatment differences persisted for insulin and IGF-I, but not for the other hormones. Increased frequency of udder emptying increased milk production, and suckling was superior to machine-milking. High milk production was associated with elevated growth hormone, IGF-I, prolactin, and oxytocin, although cause and effect could not be established. The failure of suckled cows to increase feed intake to match output requires further investigation.
Forty Holstein heifer calves were assigned to two treatments. Control calves (n = 20) were fed milk replacer in open buckets, and calves that were allowed to suckle (n = 20) were paired and suckled the same dam three times daily. Treatments were conducted during the first 6 wk following birth; thereafter, all calves received the same management, and weaning was at 60 d of age. During treatment, calves that were allowed to suckle had significantly higher average daily gains than did control calves. However, at 12 wk of age, calves that were allowed to suckle had significantly lower body weights (BW) than did control calves. Age at conception was significantly lower, and BW at conception and conception rate tended to be higher, for calves that were allowed to suckle. Calving age was significantly earlier for heifers that had been allowed to suckle as calves, and BW at calving also tended to be higher. Height at the withers after calving was also significantly higher for those heifers. Milk production during first lactation tended to be higher for the heifers that had been allowed to suckle as calves. Our results indicated that heifer calves that suckled milk during the first 42 d of age had higher average daily gains, higher height at the withers, an earlier age at calving, and a tendency for greater milk production than did calves fed milk replacer.
Two experiments examined effects of GnRH administered within 3 h after onset of estrus (OE) on ovulation and conception in dairy cows. In experiment 1, 46 cows received either saline, 250 microg of GnRH, or 10 microg of the GnRH analogue, Buserelin. Cows were observed for estrus, blood samples were collected, and ovulations were monitored by ultrasound. In controls, 76% of cows had intervals from estrus to ovulation of < or = 30 h and 24% had intervals > 30 h. Treatment with either GnRH or GnRH analogue (data combined) increased magnitude of LH surges and decreased intervals from estrus to LH surge or to ovulation. Treated cows all ovulated < or = 30 h after OE. Among control cows, plasma estradiol concentrations before estrus correlated positively with amplitudes of LH surges. Higher plasma progesterone was observed in the subsequent estrous cycle in GnRH-treated cows compared to control cows with delayed ovulations. Experiment 2 included 152 primiparous and 211 multiparous cows in summer and winter. Injection of GnRH analogue at OE increased conception rates (CR) from 41.3 to 55.5% across seasons. In summer, GnRH treatment increased CR from 35.1 to 51.6%. Across seasons, GnRH increased CR from 36.0 to 61.5% in cows with lower body condition at insemination and GnRH increased CR (63.2 vs. 42.2%) in primiparous cows compared to controls. Use of GnRH eliminated differences in CR for cows inseminated early or late relative to OE and increased CR in cows having postpartum reproductive disorders. In conclusion, GnRH at onset of estrus increased LH surges, prevented delayed ovulation, and may increase subsequent progesterone concentrations. Treatments with GnRH increased conception in primiparous cows, during summer, and in cows with lower body condition.
Mixtures of different Cannabis sativa phytocannabinoids are more active biologically than single phytocannabinoids. However, cannabis terpenoids as potential instigators of phytocannabinoid activity have not yet been explored in detail. Terpenoid groups were statistically co-related to certain cannabis strains rich in Δ9-tetrahydrocannabinolic acid (THCA) or cannabidiolic acid (CBDA), and their ability to enhance the activity of decarboxylase phytocannabinoids (i.e., THC or CBD) was determined. Analytical HPLC and GC/MS were used to identify and quantify the secondary metabolites in 17 strains of C. sativa, and correlations between cannabinoids and terpenoids in each strain were determined. Column separation was used to separate and collect the compounds, and cell viability assay was used to assess biological activity. We found that in “high THC” or “high CBD” strains, phytocannabinoids are produced alongside certain sets of terpenoids. Only co-related terpenoids enhanced the cytotoxic activity of phytocannabinoids on MDA-MB-231 and HCT-116 cell lines. This was found to be most effective in natural ratios found in extracts of cannabis inflorescence. The correlation in a particular strain between THCA or CBDA and a certain set of terpenoids, and the partial specificity in interaction may have influenced the cultivation of cannabis and may have implications for therapeutic treatments.
The effects of naturally occurring subclinical chronic or clinical short-term mastitis on time of ovulation, plasma steroid and gonadotropin concentrations, and follicular and luteal dynamics were examined in 73 lactating Holstein cows. Cows were sorted by milk somatic cell count and bacteriological examination into an uninfected group (n=22), a clinical mastitis group (n=9; events occurring 20+/-7 d before the study), and a subclinical chronic mastitis group (n=42). In addition, uninfected and mastitic cows were further sorted by their estrus to ovulation (E-O) interval. About 30% of mastitic cows (mainly subclinical) manifested an extended E-O interval of 56+/-9.2h compared with 28+/-0.8h in uninfected cows and 29+/-0.5h in the other 70% of mastitic cows. In mastitic cows with extended E-O interval, the concentration of plasma estradiol at onset of estrus was lower than that of uninfected cows or mastitic cows that exhibited normal E-O intervals (3.1+/-0.4, 5.8+/-0.5, and 5.5+/-0.5 pg/mL, respectively). The disruptive effect of mastitis on follicular estradiol probably does not involve alterations in gonadotropin secretion because any depressive effects of mastitis on pulsatile LH concentrations were not detected. Cortisol concentrations did not differ among groups. The preovulatory LH surge in mastitic cows with delayed ovulation varied among individuals, being lower, delayed, or with no surge noted compared with the normal LH surge exhibited by uninfected cows or mastitic cows with normal E-O interval (6.8+/-0.7 ng/mL). The diameter of the second-wave dominant follicle was larger and the number of medium follicles was smaller in uninfected and subclinical cows with normal intervals compared with subclinical cows with extended intervals (13.4+/-0.5 vs. 10.9+/-0.9mm, and 3.8+/-0.2 vs. 6.7+/-0.14 follicles, respectively). Mid-luteal progesterone concentrations were similar in uninfected and mastitic cows. These results indicate for the first time that around 30% of cows with subclinical chronic mastitis exhibit delayed ovulation that is associated with low plasma concentrations of estradiol and a low or delayed preovulatory LH surge.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.