Production performance of dairy cattle administered recombinantly derived bovine somatotropin (USAN, Somavubove) daily: a dose range study.

Herds (n = 9) were used on which cattle (n = 598) received 0, 4.3, 8.6, 12.9 or 17.2 mg of recombinant bovine somatotropin (rbST; USAN, Somavubove) daily from about 75 d postpartum until lactation end. Minimum effective dose to increase (3.5% fat corrected milk) FCM of cows (multiparous) compared with controls is 2.0 mg rbST/d and maximum is 16.6 mg/d. Minimum effective dose to increase FCM of heifers (primiparous) is 5.0 mg rbST/d while the maximum is 16.7 mg/d. Dosing of 4.3 to 13.2 mg rbST/d enhances efficiency of FCM production in cows. Milk fat, protein, calcium and phosphorus were not effected by rbST except for instances of transient changes. Lactose was greatest in heifers given 12.9 mg rbST/d. Days of lost milk, incidents of mastitis, and somatic cell counts were not affected by rbST. Cows given 12.9 or 17.2 mg of rbST had reduced pregnancy and conception rates, whereas heifers did not. Total services, first service conception rate, services per conception, days open and days to first AI (artificial insemination) were not affected by rbST. Days between AI were greater in cows given 17.2 mg rbST/d. Restoration of body weight and condition occurred at slower rates in rbST-dosed cows. Heifers given 8.6 or 12.9 mg rbST/d gained more weight than controls. Net energy and protein balance was reduced (less so in heifers) near start of rbST but recovered as intakes increased. Cattle given rbST produce more milk than controls and should be managed accordingly.

A review of patterns of change in luteal function.

Puberty: For the gilt and filly, the first corpus luteum (CL) appears to have a normal lifespan. For both species, first CL usually is associated with estrus but can form in the absence of estrus. For the ewe and cow, a transient (1 to 4 d, ewe; 3 to 10 d, cow) rise and fall of ovarian derived progesterone (P4) is detected in peripheral blood (80% of ewes; 50% of heifers) prior to first "normal" CL. The first CL of apparent normal lifespan is not accompanied by estrus in the ewe. The first CL in the cow may or may not be accompanied by estrus; first estrus in the cow can be anovulatory. Data are required to describe definitively variation in lifespan of first CL in these species. Persistent CL: Data that the CL can be prolonged in the absence of uterine abnormality are strongest in the mare, suggestive for the ewe under conditions of "more constant light," equivocal in the cow, and not reported in the pig. First CL after the anovulatory season: As reported for the pubertal ewe, the anestrous ewe can have a progesterone rise over a 2- to 4-d interval at about 25 d before estrus. The ewe has a P4 pattern similar to that of a normal estrous cycle in the absence of estrus immediately prior to the first estrus and CL. CL lifespan was reported for the first estrous cycle to be both normal and on the order of 4 to 10 d in up to 50% of the ewes, following introduction of rams. For the mare, first CL usually is associated with estrus and has a normal lifespan. Data suggest no P4 rise prior to first CL. The occurrence of estrus without formation of a CL is usual during the anovulatory season and during the transition from anovulatory to ovulatory seasons. Postpartum: The CL of pregnancy regressed at parturition and was not functional postpartum in the sow and cow, regressed at about d 180 of gestation in the mare (both primary CL and secondary CL), and regressed after d 140 of gestation and before d 2 postpartum in the ewe. Postpartum estrus occurring within d 1 to 3 postpartum was anovulatory for both the sow and ewe; postpartum estrus within d 5 to 12 was ovulatory for the mare.(ABSTRACT TRUNCATED AT 400 WORDS)

What is the pharmaceutical industry doing, and what does the pharmaceutical industry want from animal science departments?

Perceived contemporary issues are 1) food safety and food healthfulness, 2) environment, 3) sustainability, 4) biotechnology, 5) animal well-being, 6) animals as food, and 7) research funding. Food safety is the paramount contemporary issue, and environment and sustainability issues can be considered as a single issue. Biotechnology, animal well-being, and animals as food are addressed in this paper as separate issues, but they can be considered as components of food safety and healthfulness. The pharmaceutical industry addresses these issues by providing safe and effective products to the livestock industry. These products are used to treat and prevent disease and to increase livestock production efficiency. These products contribute to a safe food supply, enhance protection of the environment, and increase the sustainability of animal agriculture through increased efficiency of livestock production. The pharmaceutical industry wants the following from animal science departments: 1) students skilled in deductive and inductive thinking and communicating to peers and the public; 2) regional research on food safety, such as irradiation, steaming of carcasses, E. coli contamination, antibiotic resistance, production facilities, and carcass contamination; 3) improved research to identify the food values of animal products and effective communication of that research to the public; 4) research on topics having the greatest potential to increase efficiency of animal production consistent with a positive impact on the environment and sustainability of animal production; 5) leadership in developing and using technologies such as biotechnology, not only as descriptors of biological processes, but as technologies to test hypotheses leading to new understandings of biology; 6) research on animal well-being and production facilities that foster animal well-being; 7) research and education on ethical and moral aspects of animals as food through encouragement of one or more staff members to become effective animal science department spokespersons; and 8) active participation in activities such as FAIR 95, Federation of Animal Science Societies, and multidepartmental and(or) interdisciplinary programs.

Response of postpartum beef cows to exogenous progestogens and gonadotropin releasing hormone.

Plasma progesterone (P4) profile and estrous detection were used during three experiments to evaluate the effects of exogenous progestogens on the life span of gonadotropin releasing hormone (GnRH)-induced corpora lutea (CL) in postpartum (pp) beef cows. Experiment 1 utilized primiparous fall-calving cows (n = 28, trial 1); and spring-calving cows (n = 29, trial 2). On d 18 to 27 pp (d 0) all cows received intravaginal devices containing either P4 or no P4 (NP) for 5 d. On d 5 the devices were removed and calves were either removed (CR) or were present (CP) with half of the cows within steroid group. At 50 h after device removal, 500 micrograms of GnRH was given (iv) to all cows, and weaned calves were reunited with their dams. The induced CL had a normal life span (greater than 16 d) in 17 and 86% (trial 1) and 8 and 79% (trial 2) of NP and P4 cows, respectively. Calf removal did not affect (P greater than .10) the life span of the CL. In Exp. 2, spring-calving multiparous cows (d 18 to 24 pp; d 0) received either no P4 (NP; n = 19), P4 for 6 d via intravaginal devices (P4H; n = 19) or a single im injection of 300 mg P4 (P4 IM; n = 18). At 48 h after device removal or at 8 d after the injection of P4, half of the cows within steroid group received either 500 micrograms GnRH or saline. Corpora lutea had a normal life span in 0, 11, and 80% of NP, P4 IM and P4H cows, respectively, that received GnRH and in 22% of P4-saline cows. In Exp. 3, fall-calving multiparous and primiparous cows (d 25 to 31 pp) received either no progestogen (NP; n = 20), P4 via intravaginal devices for 5 d (P4H; n = 21) or melengestrol acetate (MGA; .5 mg.head-1.d-1 for 5 d orally, n = 15). At 48 d after device removal or at 72 h after the last MGA feeding, all cows received 500 micrograms GnRH. Progesterone post-GnRH injection was increased (greater than 1 ng/ml) at d 7 in 64, 100 and 100%, and remained elevated at d 14 in 11, 46 and 100% of NP, MGA and P4H cows, respectively. For all experiments plasma P4 was increased (range 2 to 5 ng/ml) when the devices containing P4 were in place, then decreased (less than 1 ng/ml) by 48 to 50 h after device removal.(ABSTRACT TRUNCATED AT 400 WORDS)

A dose-response study of melengestrol acetate on feedlot performance and carcass characteristics of beef steers.

The dose response of melengestrol acetate (MGA) on ADG (kg/d) and gain efficiency (gain/DMI, g/kg) was estimated in beef steers fed a finishing diet under commercial feedlot conditions. Melengestrol acetate is not approved for use in steers as a feed additive. The study design was five blocks of four pens (each pen was assigned a dose of MGA) with 166 to 200 steers per pen. Melengestrol acetate was fed to steers at 0 (n = 899, five pens), 0.1 (n = 900, five pens), 0.2 (n = 899, five pens), and 0.4 (n = 900, five pens) mg of MGA/steer daily. Pens within a block were slaughtered on the same day. Blocks 1 through 5 were fed MGA for 123, 122, 116, 124, and 138 d, respectively. The experimental unit was a pen of steers, and blocking was based on source of steers. The ADG was 1.81, 1.85, 1.80, and 1.83 kg/d for steers fed 0, 0.1, 0.2, and 0.4 mg MGA per day, respectively. For ADG, the dose was significant, but neither linear nor quadratic effects were significant. Compared with steers of the control group, ADG was greater for steers fed 0.1 mg MGA (P < 0.01). Feed efficiencies were 170, 173, 171, and 172 g/kg for steers fed 0, 0.1, 0.2, and 0.4 mg MGA/d, respectively; however, no effects of dose (P = 0.19) or linear (P = 0.21) or quadratic (P > 0.60) effects were observed. There was no evidence for either positive or negative effects of MGA on DMI, hot carcass weight, dressing percent, quality grade, yield grade, back fat thickness, marbling score, longissimus muscle area, and incidence of dark cutter carcasses in response to feeding MGA to steers at doses of 0.1, 0.2, and 0.4 mg daily. The incidence of buller behavior (0.43 to 1.11%) was low and did not permit an accurate test of the clinical observations that feeding MGA to steers decreases the occurrence of buller steers. Melengestrol acetate fed to finishing beef steers produced small improvements in growth performance (ADG, 2.2%) at the 0.1 mg MGA dose, but none of the doses examined produced improvement in carcass quality or yield grade measurements.

Pharmacologic and toxicologic study of prostaglandin F2alpha in cattle.

Prostaglandin F 1alpha (tham salt formulation) was injected IM into mature beef heifers at the rate of 0, 25, 75, 125, or 250 mg (4 heifers/dose group) on days 2 and 10, or 0 and 25 mg (4 heifers/dose group) on days 1 through 10. Drug effects were evaluated by means of 19 clinical observations, measurements of body weight and 10 organ weights, 15 clinical chemistry measurements, 9 hematologic measurements, 7 urinalysis measurements, and gross and microscopic observations of 27 tissues. Prostaglandin F2alpha administered on days 1 and 10 or daily for 10 days produced little evidence of pharmacologic effects and no evidence of toxicologic effects. Pharmacologic effects included a slight transitory increase in heart rate in all treated groups and slight hyperthermia in the 250-mg group. Failure to produce important toxicologic effects at 250 mg/day and with luteolytic doses occurring around 15 to 25 mg/day demonstrated that the safety factor was in excess of 10 X.

Multi-state Beef Reproduction Task Force provides science-based recommendations for the application of reproductive technologies.

Since its formation, the Beef Reproduction Task Force (BRTF) has worked to enhance productivity and profitability of US beef herds by integrating research and extension efforts with the intent of more effectively transferring the use of reproductive technologies to the field. A key early step was to coordinate efforts in identifying effective breeding management protocols for beef cattle and to clarify their associated acronyms. A short list of recommended protocols and their acronyms for synchronization of estrus and ovulation in beef cattle was developed based on results from peer-reviewed, published research and a comprehensive review of data collected from the field. The list of recommended protocols was developed by the BRTF in cooperation with veterinarians and cattle AI industries. These protocols and their acronyms are presented uniformly in all of the major AI sire directories and are available online at http://www.beefrepro.info. Protocol updates are made annually to incorporate the most recent research findings related to estrous cycle control in beef cattle. The Estrus Synchronization Planner, a software program developed in cooperation with the Iowa Beef Center, now reflects these same recommendations. Beginning in 2002, the BRTF hosted and presented 11 educational workshops to more than 1,900 attendees in key cow-calf states. These Applied Reproductive Strategies in Beef Cattle workshops targeted beef producers, AI industry personnel, veterinarians, allied industry representatives, and academicians. A national media sponsor provided online coverage of the last 3 workshops at http://www.appliedreprostrategies.com. A postmeeting evaluation, developed to assess application of information from 2 recent workshops, was returned by 55% of those contacted (n = 150). Attendees averaged 16 (± 13.4 SD) yr of AI experience, and 80% of respondents represented more than 100 cows. Respondents were asked to estimate the value of AI-sired calves compared with natural-service-sired calves to their operation on a per-animal-marketed basis, and 17 and 31% responded $50 to $100 per animal and more than $100 per animal, respectively. As a result of what was learned at these conferences, 78% of respondents were better able to troubleshoot management-related issues, 60% made alterations to a protocol they had been using, and 35% of the respondents indicated they changed to a different estrus synchronization protocol.

ASAS centennial paper: Contributions in the Journal of Animal Science to the development of protocols for breeding management of cattle through synchronization of estrus and ovulation.

American Society of Animal Science members, publishing in Journal of Animal Science (JAS), completed research that resulted in understanding the estrous cycle of cattle, which led to the ability to inseminate cattle on a given day with pregnancy rates similar to those achieved by 21-d breeding by a fertile and sound bull. Research published in JAS led to understanding estrus, ovulation, the estrous cycle, and postpartum interval for cattle (1930s through 1960s) and hormonal factors affecting corpus luteum lifespan of cattle (1950s through 1980s). Research during the 1940s to 1960s, using gonadotropins and progesterone to manage the estrous cycle of cattle, established the concepts for estrous synchronization and stimulated commercial research directed at developing cost-effective progestogen estrous synchronization products, leading to commercially available products from 1967 through today (Repromix, melengestrol acetate, Syncro-Mate-B, controlled internal drug release). Prostaglandin F(2alpha) products were approved for estrous synchronization (1970s, 1980s), and GnRH products were approved for use in cattle to treat ovarian follicular cysts (1970s, 1980s). Research published in JAS was essential for understanding the biology of and potential value of both PGF(2alpha) and GnRH and contributed both to new knowledge and scientific bases for future Food and Drug Administration Center for Veterinary Medicine approval of those products. Research during the1980s through 2000s led to understanding ovarian follicular waves and described the timing of follicular recruitment, selection, dominance, and atresia; this research was essential for the ability to effectively manage follicles to achieve success with timed AI. The knowledge gained through research published in JAS resulted in development of the numerous estrous synchronization and breeding management protocols that are cost-effective and meet the breeding management needs of most beef and dairy enterprises.

Industry's responsibility to the consumer.

The responsibility of industry to the consumer is to provide products derived from biotechnology that are effective as labeled and safe for their intended use on animals, plants and in the environment. Moreover, food products from the animals and plants receiving the drugs or chemicals must be safe for human consumption. To fulfill these responsibilities, industry must provide an accurate label for the drug or chemical, ensure drug or chemical product consistency so that every batch of the drug or chemical is similar to every other batch, complete studies to document that the drug or chemical is safe for use in the animal or on the plant, complete studies designed to provide data to ensure that the food derived from the use of the drug or chemical is safe for human consumption and complete studies to document that the drug or chemical is safe for use in the environment. The process of requiring data to be derived from sound experimental science, completion of the studies under scrutiny by regulatory personnel and extensive scientific review of the data by regulatory personnel results in products derived from biotechnology that are safe and effective.

Prostaglandin E1 and F2alpha specific binding in bovine corpora lutea: comparison with luteolytic effects.

Preliminary characterization indicated the presence of separate prostaglandin (PG)E1 and (PG)F2alpha binding sites in membrane fractions prepared from bovine corpora lutea. These differ in the rate and temperature dependence of the specific binding. Equilibrium binding data indicate the apparent dissociation constants as 1.32 x 10(-9)M and 1.1 x 10(-8)M for PGE1 and PGF2alpha, respectively. Competition of several natural prostaglandins for the PGE1 and PGF2alpha bovine luteal specific binding sites indicates specificity for the 9-keto or 9alpha-hydroxyl moiety, respectively. Differences in relative ability to inhibit 3H-PG binding were found due to sensitivity to the absence or presence of the 5, 6-cis-double bond as well. Bovine luteal function was affected following treatment of heifers with 25 mg PGF2alpha as measured by reduced estrous cycle length, decreased corpus luteum size and significantly decreased plasma progesterone levels. In contract, treatment with 25 mg PGE1 resulted in cycle lengths comparable to those of non-treated herdmates with no apparent modification in corpus luteum size. However, plasma progesterone levels were increased significantly following PGE1 treatment compared to pretreatment values. In so far as data obtained in vitro on PGF2alpha relative binding affinity to the bovine CL can be compared to data obtained independently in vitro on PGF2alpha induced luteolysis in the bovine, PGF2alpha relative binding to the CL and luteolysis appeared to be associated. By similar reasoning, there was no apparent relationship between PGE1 relative binding affinity in the luteal fractions and luteolysis in estrous cyclic cattle.

Milk yield, health, and reproduction of dairy cows given somatotropin (Somavubove) beginning early postpartum.

Cows (n = 210) were assigned to the following treatments: uninjected controls through 130 d postpartum; zero to high, uninjected through 60 d then injected with 14 mg of bST/d from 61 through 130 d postpartum; low, 5 mg of bST/d from 14 through 130 d postpartum; low to high, 5 mg of bST/d from 14 through 60 d then 14 mg of BST/d from 61 through 130 d postpartum; and high, 14 mg of bST/d from 14 through 130 d postpartum. Cows given 5 mg of bST/d (low and low to high treatments) yielded 1.2 kg of FCM/d more and high group cows yielded 1.3 kg of FCM/d more than control cows between 14 and 60 d postpartum. Cows given bST yielded 2.7 to 4.1 kg of FCM/d more than control cows during 61 to 130 d postpartum. Overall, control cows yielded 35.1 kg of FCM/d, and bST-dosed cows yielded 2.2 to 3.2 kg/d more FCM. Low group cows had improved pregnancy rate (80.0%) and conception rate (82.2%) compared with high group cows (57.2 and 60.3%). Neither pregnancy (70.0%) nor conception rates (71.5%) of controls differed from other groups. However, low group cows had first service conception rate of 57.8% compared with 34.3% for high and 38.2% for low to high group cows. First postpartum estrus was observed in high group cows about 13 to 16 d later than in low and low to high group cows, whereas low group cows came into first estrus 9 d sooner than controls. Cows of high group had lower body condition than controls (2.5 vs. 2.9), but other groups did not differ (2.7 to 2.9) from controls. Health was not adversely affected. Early postpartum bST administration at 5 mg/d increases FCM and, perhaps, reproductive performance of dairy cattle compared with herdmates.

Milk yield of dairy cows receiving somatotropin (somavubove) daily with periodic 14-day interruption.

Thirty multiparous (cows) and 15 primiparous (heifers) lactating Holstein cattle were used in a 112-d study to examine the effects of pattern of administration of recombinantly derived bST on 3.5% FCM yield. Ten cows and 5 heifers each received either no injection (controls), 14 mg of bST daily, or four repetitions of 14 mg of bST/d for 14 d followed by 14 d of no injection (intermittent bST). Because there was an interaction between treatment groups and parity, analyses were performed separately for cows and heifers. All cows and heifers produced more FCM when given bST than controls. Comparing FCM only during the last 7 d of each period of injection for the intermittent bST group with contemporary daily injected cattle indicated that cows produced equivalent amounts of milk at those times, whereas heifers given daily bST produced 3.4 kg/d more than intermittently injected animals. Furthermore, over each of the four repetitive periods, cows and heifers given daily or intermittent bST responded similarly, although heifers given continuous bST produced more FCM than the intermittent group during each of periods 2 through 4. We conclude that daily administration of bST lends itself to dosing termination during established lactation with concomitant decline of FCM; resumption of bST allows milk yields of cows to achieve levels comparable with those prior to short-term interruption.