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Kansas State University

 

Beef Research News
Brought to you by Kansas State University College of Veterinary Medicine - Farm Animal Section
March 2008

 

 

 

Contents:

Fresh steps taken in bovine orthopedics

Sire effect on fixed-time AI pregnancy outcome

Effects of long and short term exposure to BVD-PI in feedlot heifers

Comparison of heifer estrus synchronization programs

Neck injection and handler visibility effect on cattle behavioral reaction

BCS effect on endocrine and ovarian factors in post-partum beef cows



Fresh steps taken in bovine orthopedics

Fresh steps are being taken in bovine orthopedics and also by a Jersey cow named Wilhemenia Jolene, thanks to Dr. David Anderson and his team. Dr. Anderson, professor and head of Farm Animal, is launching a new cruciate ligament replacement for cattle, called the Wildcat Power Cord.

“I am proud to be able to announce that K-State is able to provide a life-saving and genetics-saving service to our clients who have valuable cattle suffering from stifling injuries,” Dr. Anderson said. “The Wildcat Power Cord offers a solution to culling valuable genetic stock. The first case has progressed beyond expectations, and we are excited to offer this to our valued clients."

Wilhemenia had a ruptured cranial cruciate ligament in her right knee. The surgery took place on Jan. 17, and Wilhemenia is doing extremely well.


Sire effect on fixed-time AI pregnancy outcome

The objective was to determine the sire effect on the pregnancy outcome in beef cows in which stage of estrus was synchronized with progesterone based fixed-time artificial insemination (AI) protocols. Three Angus sires with more than 300 breedings were evaluated for differences in pregnancy outcome from 1868 inseminations. Angus cross beef cows (N = 1868) were synchronized with Ovsynch-CIDR or CO-Synch-CIDR protocols for fixed-time AI. Cows in both groups that showed estrus on day 9 before 1500 h were designated to Selectsynch-CIDR group and were inseminated according to AM-PM rule. Results indicated that Sire 2 had lower fixed-time AI pregnancy rate compared to Sire 3 (48.1% versus 58.7%; P = 0.01). Significant sire × synchronization program and sire × location interactions were observed for fixed-time AI (P < 0.05). Sire 2 had a lesser fixed-time AI pregnancy in both Ovsynch-CIDR and CO-Synch-CIDR groups compared to Sire 3. In two of four locations, Sire 2 had a lesser fixed-time pregnancy rate compared to Sire 3. No sire differences were observed in AI pregnancy for cows in Selectsynch-CIDR group.

In the present study, no differences in the PR for fixed-time AI among locations were observed (P > 0.05). However, there was a sire × location interaction observed (P < 0.05). Sire 2 had lesser pregnancy compared to Sire 3 in two of four locations. This indicates that other factors like environment and inseminator might play a role. The effect of inseminator on the PR within farm was not different. In conclusion, evidence in this study suggest that there are differences in sire fertility when they were used in fixed-time AI protocols, possibly due to the sire differences in sperm capacitation process. Further studies are needed to investigate association of the sire differences in fixed-time AI protocols with sire differences in the sperm capacitation process.

Kasimanickam, R. J. Hall, J. Currin, W. Whittier Sire Effect on the Pregnancy Outcome in Beef Cows Synchronized with Progesterone Based Ovsynch and CO-Synch Protocols Anim Repro Sci February 2008 Vol. 104, No. 1, pp. 1-8.


Effects of long and short term exposure to BVD-PI in feedlot heifers


A single experiment with a completely randomized design was conducted to evaluate the effects of long- or short-term exposure to a calf identified as persistently infected with bovine viral diarrhea virus (PI-BVD) on feedlot performance and carcass characteristics of freshly weaned, transport-stressed, beef heifers. Two hundred eighty-eight heifers that had been vaccinated for BVD before weaning and transport were processed and given a metaphylactic antibiotic treatment at arrival and fed common receiving, growing, and finishing diets for a 215-d period.

Treatments were designed to either directly or adjacently expose the cattle to a PI-BVD heifer. Directly exposed treatments were: 1) negative control with no PI-BVD calf exposure (control, CON); 2) PI-BVD calf commingled in the pen for 60 h and then removed (short-term exposure, STE); and 3) PI-BVD calf commingled in the pen for the duration of the study (long-term exposure, LTE), and spatially exposed treatments were: 1) negative control with no PI-BVD calf exposure (adjacent pen control, APC); 2) PI-BVD calf commingled in the adjacent pen for 60 h and then removed (adjacent pen short-term exposure, APS); and 3) PI-BVD calf commingled in the adjacent pen for the duration of the study (adjacent pen long-term exposure, APL).

Exposure to a PI calf either transiently (60 h) or for the duration of the feeding period (215 d) did not affect (P 0.25) final BW compared to heifers that were not exposed. Neither period nor overall DMI was affected (P 0.37) by PI-BVD calf exposure, and no differences (P 0.44) were observed between short- and long-term exposed heifers in either the direct or spatially exposed groups. Likewise, total trial ADG was not affected (P 0.36) and overall feed efficiency (P 0.19) was unaffected by PI-BVD calf exposure in either the direct or spatially exposed groups. Results from this study suggest that exposing previously vaccinated, freshly weaned, transport-stressed, beef calves to a calf that is persistently infected with bovine viral diarrhea virus has little, if any, marked affects on health, performance, and carcass characteristics.

Elam, N.A., D. U. Thomson, J. F. Gleghorn. Effects of long- or short-term exposure to a calf identified as persistently infected with bovine viral diarrhea virus on feedlot performance of freshly weaned, transport-stressed, beef heifers J. Anim Sci. 1910. 0:jas.2007-0535v1. doi:10.2527/jas.2007-0535 Published online first on March 14, 2008.


Comparison of heifer estrus synchronization programs

The objective of the experiment was to compare follicular dynamics, ovulatory response to GnRH, and synchrony of estrus and ovulation among estrous cycling and prepubertal beef heifers synchronized with a controlled internal drug release (CIDR)-based or GnRH-PGF2 (PG) protocols. Estrous cycling beef heifers were randomly assigned to 1 of 4 treatments (C1, C2, C3, C4) and prepubertal beef heifers were randomly assigned to 1 of 2 treatments (P1, P2) by age and BW. Blood samples were taken 10 and 1 d before treatment to confirm estrous cyclicity status (progesterone 0.5 ng/mL estrous cycling). CIDR Select (C1, n = 12; P1, n = 14) treated heifers received a CIDR insert (1.38 g progesterone) from d 0 to 14, GnRH (100 µg, i.m.) on d 23 and PG (25 mg, i.m.) on d 30.

Select Synch + CIDR (C2, n = 12; P2, n = 11) treated heifers received a CIDR insert and GnRH on d 23 and PG at CIDR removal on d 30. CIDR-PG (C3, n = 12) treated heifers received a CIDR insert on d 23 and PG at CIDR removal on d 30. Select Synch (C4, n = 12) treated heifers received GnRH on d 23 and PG on d 30. HeatWatch transmitters were fitted at CIDR removal (C1, C2, C3, P1, and P2) or at GnRH administration (C4) for estrus detection.Ultrasound was used to determine response to GnRH and timing of ovulation following estrus. Among the estrous cycling heifers, ovulatory response to GnRH and estrous response did not differ (P > 0.05). Among the prepubertal heifers, more (P = 0.02) P1 heifers responded to GnRH than P2 heifers, but estrous response did not differ (P > 0.05). Among the estrous cycling heifers, variance for interval to estrus after PG was reduced (P < 0.05) for C1 compared with each of the other treatments, and C2 was reduced (P < 0.05) compared with C3.

Variance for interval to ovulation after PG was reduced (P < 0.05) for C1 compared with each of the other treatments. Among the prepubertal heifers, there was no difference (P > 0.05) in variance for interval to estrus or ovulation. Results from C1 and P1 (T1) and C2 and P2 (T2) were combined to compare T1 and T2 among mixed groups of estrous cycling and prepubertal heifers. Response to GnRH was greater (P < 0.01; 81% T1 and 39% T2), and variances for interval to estrus and ovulation for T1 were reduced (P < 0.01) compared with T2. In summary, CIDR Select improved (P < 0.01) synchrony of estrus and ovulation compared with Select Synch + CIDR.

Leitman, N.R., D. C. Busch, J. F. Bader, D. A. Mallory, D. J. Wilson, M. C. Lucy, M. R. Ellersieck , M. F. Smith, D. J. Patterson Comparison of protocols to synchronize estrus and ovulation in estrous cycling and prepubertal beef heifers J. Anim Sci. 1910. 0:jas.2008-0970v1. doi:10.2527/jas.2008-0970 Published online first on April 11, 2008.


Neck injection and handler visibility effect on cattle behavioral reaction

The use of the neck region as injection site in cattle is becoming routine. Use of a blind may reduce aversive behavior caused by the presence of the person administering the injection. To evaluate whether cattle react to the proximity of the stockperson or to the actual injection, 120, 10-mo-old, Angus steers weighing 298 ± 28 kg (mean ± SD) were assigned to 1 of 4 treatment groups using a partial crossover design (neck/sham injection x blind/no blind) replicated over 2 d (3 d apart). Cattle were restrained for a total of 60 s in a squeeze chute with treatment being administered 20 s after entry. Animal reactivity was rated using 2 scoring methods including a visual and an electronic score for three 20-s intervals (pre-treatment, treatment, and post-treatment intervals).

Flight speed (m/s) was used as a measure of aversion to treatments and was taken upon release from the chute. No interactions (P > 0.10) were observed between the blind and injection treatments for any of the measurements taken. No treatment or day effect on flight speed (2.7 vs. 2.6 m/s; P > 0.03) was observed; however, correlation between days (r = 0.74; P < 0.001) was significant. Visual scores indicated that injected cattle were more agitated during the treatment interval than sham injected cattle (1.9 vs. 1.6, respectively) (P = 0.01). However, no differences (P > 0.10) were found between injection and sham injection treatments for any of the electronic scores. Steers exposed to the blind had lower electronic reactivity scores (P < 0.05) than those not exposed to the blind, which was in contrast to the results obtained for the visual scores (P < 0.05). Discrepancies between reactivity scores may be due to the difficulty in accurately assessing minor animal responses using the visual method. Presence of a handler during an injection procedure could be a contributor to the aversion response observed in cattle undergoing routine neck injections and use of a blind helped to reduce the reactivity in the animals.

Müller, R., K. S. Schwartzkopf-Genswein, M. A. Shah, M. A. G. von Keyserlingk. Effect of neck injection and handler visibility on behavioral reactivity of beef cattle. J. Anim Sci. 1910. 0:jas.2007-0452v1. doi:10.2527/jas.2007-0452 Published online first on February 13, 2008.


BCS effect on endocrine factors and ovarian follicles in post-partum beef cows

Multiparous beef (1/4 to 3/8 Bos indicus; n = 99) cows were managed to achieve low (BCS = 4.3 ± 0.1; n = 50) or moderate (BCS = 6.1 ± 0.1; n = 49) body condition (BC) to determine the influence of bovine (b) ST on number of follicles, diameter of largest follicle, and serum concentrations of IGF-I, triiodothyronine (T3), thyroxine (T4), and prolactin. Beginning 32 d postpartum, cows within each BC were assigned randomly to treatment with or without bST. Non-bST-treated cows received no treatment, and treated cows were administered bST (Posilac, 500 mg, s.c.) on d 32, 46, and 60 postpartum.

On d 60, all cows received a controlled internal drug-releasing (CIDR) device for 7 d and PGF2 at CIDR removal (CIDR-PGF2 ). Blood samples (7 mL) were collected at each bST treatment and d 39 and 67 postpartum. Ultrasound was performed 1 d after CIDR-PGF2 to determine number of small (2 to 9 mm) and large ( 10 mm) follicles, and diameter of largest follicle. Cows treated with bST in low BC had increased (P < 0.05) IGF-I vs. low BC-non-bST-treated cows on d 39, 46, 60, and 67 postpartum. Prolactin and T3 were greater (P < 0.05) in moderate BC than low BC cows on all sample dates.

Thyroxine was greater (P < 0.001) in moderate BC cows on d 46, 60, and 67 compared with low BC cows. On d 67, bST-treated cows had greater (P < 0.05) T4 compared with non-bST treated cows. Diameter of the largest follicle 1 d after CIDR-PGF2 was greater (P < 0.01) in anestrous cows treated with bST than for non-bST-treated-anestrous cows. Diameter of largest follicle was correlated with concentrations of IGF-I (r 0.18; P 0.08), T3 (r 0.17; P 0.10), and prolactin (r 0.20; P .05). Treatment with bST increased IGF-I in low BC cows, and IGF-I was correlated with diameter of the largest follicle 1 d after CIDR-PGF2 . Undernutrition of cattle may be communicated to the hypothalamic-pituitary-ovarian axis via metabolic hormones that include IGF-I, thyroid hormones and (or) prolactin.

Flores, R., M. L. Looper, R. W. Rorie, D. M. Hallford, C. F. Rosenkrans Jr.. Endocrine factors and ovarian follicles are influenced by body condition and somatotropin in postpartum beef cows J. Anim Sci. 1910. 0:jas.2007-0574v1. doi:10.2527/jas.2007-0574 Published online first on February 13, 2008


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