Resynchronization of estrus in beef cattle: ovarian function, estrus and fertility following progestin treatment and treatments to synchronize ovarian follicular development and estrus

The objective was to optimize rebreeding of nonpregnant, previously inseminated beef cattle. In Experiment 1, 43 cows received a used intravaginal progesterone-releasing insert (IVPRI; Days 0-7) 12.3 d after ovulation and received concurrently no treatment, 100 microg gonadotropin releasing hormone (GnRH), 1 mg estradiol cypionate (ECP), or 150 mg progesterone. Emergence of a new ovarian follicular wave was most synchronous (P < 0.0001) in the GnRH group. In Experiment 2, 675 heifers were given GnRH or no treatment on Day 0, fed melengestrol acetate (MGA; 0.5 mg/head/d) from Days 0-5 (Day 0 = 13-14 d after timed insemination; TAI), given 0.5 mg ECP or nothing on Day 7, and reinseminated 6-12 h after onset of estrus. Estrus was more synchronous (P < 0.05) in heifers given GnRH versus no treatment on Day 0. In Experiment 3, 317 TAI heifers were resynchronized with either MGA or a used IVPRI with or without ECP on Day 7; estrus was more synchronous (P < 0.05) and pregnancy rates were higher (54.1% versus 39.2%, P < 0.05) in heifers given a used IVPRI than those fed MGA. For resynchronization of heifers, pregnancy rates were not significantly improved with GnRH treatment, but were higher with a used IVPRI than with MGA.     

Occurrence of mastitis and associated risk factors in lactating goats under pastoral management in Borana,Southern Ethiopia

Mastitis prevalence and related risk factors were studied in 1,072 udder halves of 536 lactating goats from October, 2008 to February, 2009. Clinical and subclinical mastitis were prevalent in 4.3% (95% CI = 2.8, 6.5) and 11.2% (95% CI = 8.7, 14.3) of the studied animals, respectively, resulting in an overall prevalence of 15.5% (95% CI = 12.6, 18.9). Univariate analysis of the potential risk factors has depicted that mastitis was more prevalent in does with previous mastitis history, increased parity, poor body conditions, increased milk production, late lactation stage, long teat, and housed goats. Furthermore, prevalence was significantly higher (p < 0.05) during the wet period of October to November than the dry periods of January to February. No significant variations (p > 0.05) were observed in mastitis prevalence with udder tick infestation, mixing goat with sheep and flock size. With multivariable analysis, lactation stage, teat length, body condition, and season (wet months) have showed significant association with mastitis prevalence, and these factors maintained significant in the stepwise elimination of multivariable logistic regression model. As a result, does in late stage of lactation (OR = 4.3, 1.8, 10.4), poor body condition (OR = 5.0, 1.7, 10.0), long teats (OR = 2.2, 95% CI = 1.1, 4.2) and does examined in wet period were at higher risk of udder infections than early lactation, good body condition, short teat, and examined in dry period, respectively. The study showed occurrence of mastitis and associated risk factors in studied goats, which suggests the need for control intervention. Further investigations into pathogens involved in goat mastitis will optimize our knowledge of causative agents and control interventions.     

Influences of non-genetic factors on early growth of Adilo lambs under smallholder management systems,southern Ethiopia

Stagnant early growth and mortality are the major impediments for sheep production in southern Ethiopia. We evaluated the effects of non-genetic factors on early growth performance of lambs in Halaba district with 467 lambs owned by 60 households. Body weights (kilograms) of lambs at birth, 30, 60, 90, 120, and 150 days were 2.30 ± 0.03, 4.45 ± 0.11, 6.94 ± 0.13, 10.4 ± 0.19, 13.3 ± 0.19, and 15.7 ± 0.20, respectively. The average daily gain (ADG; gram) from birth to 30, 60, 90, 120, and 150 days were 71.18 ± 8.18, 77.18 ± 2.19, 89.20 ± 1.98, 91.18 ± 1.51, and 90.68 ± 1.27, respectively. Season effect was significant (p < 0.05) for weight at birth, 30, and 120 days. Similarly, season of birth influenced (p < 0.05) ADG (gram) at all ages except from birth to 60 days. Single-born lambs were heavier over multiple births (p < 0.01), 90 (p < 0.001) and 120 days (p < 0.05) and higher (p < 0.001) ADG from birth to 90 days. There were significant interaction effects of parity by sex at birth (p < 0.01) and parity by type of birth (p < 0.001) and 90 days (p < 0.01). From the non-genetic factors estimated in this study, season and type of birth, and their interaction had a more profound effect at early growth of lambs, and they need to be considered in the improvement plan of sheep under Halaba arid to semi-arid environments. Efforts geared towards planned breeding, improved nutrition, and health would assist farmers to exploit these indigenous and adaptable sheep resources efficiently.     

Growth performances of Washera sheep under smallholder management systems in Yilmanadensa and Quarit districts,Ethiopia

A study was conducted to evaluate growth performances of Washera sheep under smallholder production systems in the Yilmanadensa and Quarit districts of the Amhara National Regional State, Ethiopia. Data were collected and analysed on the growth of 690 lambs owned by 110 households from October 2004 to September 2007. Weight (kilograms) of Washera lambs at birth, 1, 3, 6, 9 and 12 months of age was 2.69 ± 0.02, 7.10 ± 0.16, 12.42 ± 0.11, 16.12 ± 0.91, 20.05 ± 0.55 and 23.47 ± 0.68, respectively. Birth weight was significantly (P < 0.05) affected by district, year of birth, parity of the dam, birth type and sex of lamb and by the interaction effect of parity by birth type and parity by sex of lamb. Weaning weight was also affected by year of birth, type of birth and sex of lamb. Yearling weight was affected by only year of birth and sex of birth. The average daily weight gain (ADG; grams) from birth to 30 days, birth to 90 days, 90 to 180 days and birth to 1 year of age was 143.37 ± 13.46, 107.09 ± 2.67, 39.78 ± 9.73 and 60.13 ± 1.89, respectively. Growth rates from birth to 30 and 90 days of age were significantly (P < 0.05) affected by birth year, birth type and sex. ADG from birth to 1 year of age was affected by lamb sex and district. The indigenous Washera sheep had faster growth rate than those sheep breeds of Ethiopia extensively studied thus far. Integrated efforts combining improved nutrition, health and participatory community-based breeding would help the smallholder farmers to utilise and conserve this immense sheep genetic resource of Ethiopia.     

Growth,reproductive, and productive performance of Begait cattle under different herd management systems in northern Ethiopia

The performance of indigenous Begait cattle (498 cows, 284 calves, and 48 heifers) in northern Ethiopia was studied. System of herd management significantly (P?<?0.01) influenced all production traits. Calves in medium-input herds (MIHM) grew faster than those in low-input herds (LIHM), by 232 g/d from birth to 9 months (Gain₁) and by 385 g/d from 9 to 12 months (Gain₂). Cow’s dry period, calving interval (CI), and age at first calving (AFC) were 234, 222, and 343 days shorter for MIHM than for LIHM. Compared with LIHM, cows from MIHM had 74% higher daily milk yield (DMY) and 91% higher lactation milk yield (LMY). Calves born at wet season grew faster by 14 and 10% than those calves born in the dry season at Gain₁ and Gain₂. The subsequent CI of cows calved in the wet season had 77 days shorter, 0.45 kg DMY, and 93 kg LMY increment. The differences between production systems can be attributed to differences in management skills and access to better quality feeds. Technical intervention is needed to ensure provision of balanced rations to exploit the potential productivity of Begait cattle.     

The effect of body condition on ovarian activity of free ranging tropical jennies (Equus asinus)

Serial ultrasonography was performed on seven jennies to study the effect of seasonally fluctuating body condition on ovarian activity during the dry, short rainy and long rainy seasons. Kendall Tau correlations and differences of least square mean values were compared. A distinct seasonal pattern was observed both in body condition and ovarian activity. The mean (+/-SD) Body Condition Score (BCS) was lowest during the dry season 2.6 +/- 0.45 when compared with 3.5 +/- 0.52 and 3.9 +/- 0.58 during the short and long rainy seasons, respectively. The mean (+/-SD) number of total follicles was also proportionally low 7.3 +/- 1.6 during the dry season compared with 9.6 +/- 2.4 and 11.3 +/- 3.3 found during the short and the long rainy seasons, respectively. The BCS was positively correlated to the total number of follicles and the diameter of the largest follicle during all seasons. Periods of increasing BCS and transition between seasons with both increasing and decreasing body conditions were strongly correlated to the number and size of ovarian follicles. Seasonal fluctuation in the body condition was found to be the result of variation in feed resource and ovarian activity was also closely following this seasonal pattern. The improvement in body condition has generally, a positive impact on emergence of small growing follicles there by having influence on the total count of ovarian follicles.     

Characteristics of follicular dynamics and reproductive hormone profiles during oestrous cycles of jennies over an entire year

Although donkeys have been domesticated for over 6,000 years, limited information is available concerning their reproductive physiology, especially under intensive rearing conditions. The aims of this experiment were to study follicular dynamics and reproductive hormone variation in jennies during the inter-ovulatory interval in different seasons. A total of 12 continuous cycles of six Dezhou Black (DB) donkey jennies were examined in four different seasons. The diameters of the six largest follicles of each jenny were measured daily by ultrasonography, and blood samples were collected at fixed times for reproductive hormone assays. The results demonstrated that most jennies displayed regular oestrous cycles in all seasons. The follicular dynamics were similar in Spring, Summer and Winter, while the jennies had longer oestrous cycles with delayed follicular deviation and dominant selection in Autumn. At least two follicular waves were observed in each oestrous cycle, throughout the study, but two jennies presented oestrous cycles with three follicular waves in the Autumn. The numbers of follicular waves were consistent with the numbers of FSH surges. Oestrous characteristics of the jennies in a large herd were also analysed. The results showed that the rates of regular oestrous cycles were 83.1% (265/319), 89.6% (215/240), 80.2% (235/293) and 77.1% (178/231), with 26.4% (70/265), 19.5% (42/215), 22.1% (52/235) and 23.0% (41/178) double ovulation rates in Spring, Summer, Autumn and Winter, respectively. The results presented may be useful for donkey farms in the design of breeding strategies.     

Milk yield and reproductive performance of dairy cattle under smallholder management system in North-eastern Amhara Region,Ethiopia

This study was conducted in South Wollo Zone of Amhara Regional State, Ethiopia, to assess the milk yield and reproductive performance of indigenous and crossbred cattle under smallholder management conditions. Questionnaire survey was used to collect retrospective data on the performance of dairy cattle in 186 households. Thirty two postpartum cows (16 indigenous and 16 crossbred) were selected purposively and monitored for five months and milk samples were collected twice per week from each cow to determine postpartum ovarian activity using ELISA techniques. Daily milk yields at all stages of lactation were significantly (P < 0.01) higher in crossbred than indigenous cows. Crossbred cows had significantly (P < 0.01) longer lactation length and shorter age at first calving, while calving interval was significantly shorter in cows that gave previous calves during the wet season than the dry season. Only six cows (18.8%) showed heat signs on an average of 136 days postpartum of which one was a crossbred and five were indigenous. While, 11 cows (34.3%) resumed ovarian activity until 150^th day postpartum among which three were crossbred and eight were indigenous.     

注射国产LRH-A对产后母牛卵巢活动、发情和受胎的作用

<正> 引言 促性腺激素释放激素(GnRH)是下丘脑神经内分泌细胞分泌的一种释放激素。由于本身结构和功能上的特点,自七十年代初人工合成后,GnRH及其类似物被广泛用于牛繁殖的研究和生产中。国外有报道认为GnRH有促进产后母牛发情周期恢复,缩短产后空怀天数等作用。国内用LRH-A提早牦牛产后发情和受胎收到良好效果。     

Effects of placement of intravaginal sponges on LH, FSH, estrus and ovarian activity in mares during the nonbreeding season

Eight seasonally anestrous mares were administered intravaginal polyurethane sponges on December 15 and then weekly thereafter until February 1. Control mares received no sponges or genital contact. Sponge insertion caused an immediate surge in follicle-stimulating hormone (FSH) concentrations in jugular plasma in 50% of treated mares whereas no control mares had surges in FSH (P less than .05). The effect of treatment on luteinizing hormone (LH) concentrations was much less dramatic and only three treated mares appeared to have positive responses. Sponge-treated mares exhibited positive responses in FSH concentrations 11 times out of 32 mare-days and control mares zero out of 28 (P less than .05). The magnitude of the FSH response decreased rapidly with successive responses. Sponge insertion induced estrus in four of eight treated mares; no control mares exhibited estrus (P less than .05). Sponge insertion also increased ovarian size and the incidence of large follicles. When all mares were fed altrenogest for 14 d beginning February 1, there was no beneficial effect of sponge treatment on number of mares exhibiting estrus or on pregnancy rate. These data confirm earlier speculations that sponge treatment causes surges in gonadotropins and increased ovarian size in approximately 50% of anestrous mares. However, sponge treatment does not appear to provide a practical means of preparing mares for progestogen synchronization during the nonbreeding season.     

Seroprevalence of brucellosis and its contribution to abortion in cattle,camel, and goat kept under pastoral management in Borana,Ethiopia

The involvement of Brucella infection in causing abortion was investigated in a breeding female subpopulation of 283 cattle, 756 camels, and 757 goats. Serum samples were serially tested using the Rose Bengal test and complement fixation test. The study showed that anti-Brucella antibodies were prevalent in 10.6% (95% confidence interval (CI), 7.4, 14.9), 2.2% (95%CI, 1.4, 3.7), and 1.9% (95%CI, 1.1, 3.2) of cattle, camel, and goats, respectively. Abortion was more commonly reported in camels (23.4%) than cattle (13.8%) and goats (12.4%). The results of this study suggested that Brucella infections contribute significantly to abortion in cattle (odds ratio (OR), = 4.7; 95%CI, 2.0, 10.8) and goats (OR = 6.9; 95%CI, 2.2, 21.7) but not in camels. The number of young animals produced by breeding females seems to be apparently reduced in seropositive groups. Keeping more than two animal species at household level was found to be the risk factor for cattle (OR = 3.1; 95%CI, 1.2, 7.9) and camel (OR = 5.3; 95%CI, 1.2–23.5) seropositivity to Brucella infection when compared to those animals from households that keep only two animal species. This may suggest a possibility of cross species transmission of Brucella infection under such mixed herding. Wet season (OR = 4.8; 95%CI, 1.3, 18.1) was found to be associated with seropositivity in goats, linked to a coincidence of increased deliveries in flocks with possible excretion of Brucella organisms. The study results suggest that Brucella infection is the likely cause of abortion in cattle and goats while other causes largely outweigh brucellosis as a cause of abortion in camels in Borana, hence, contributing to reproductive loss.     

Etiopathogenesis, clinical manifestations, and management of canine silica urolithiasis

Silica uroliths were first recognized in dogs in the mid 1970s. Currently available data suggest that dietary factors may play a role in their pathogenesis. Diagnosis is facilitated by their typical jackstone appearance but must be verified by quantitative analysis. Surgery is the only feasible method of treatment.     

貉发情期卵巢和子宫解剖结构的观察

本文以发情期母貉为研究对象,借助形态学、组织胚胎学、解剖生理学等知识,对母貉发情期子宫、卵巢的形态结构进行研究,通过冰冻切片的方法,在发情期母貉的卵巢中观察到了原始卵泡、生长卵泡、囊状卵泡.经过本试验,确立了貉发情期卵巢、子宫的正常生殖变化和解剖结构,为今后的生理学和病理学的研究提供了理论基础.     

Etiopathogenesis, clinical manifestations, and management of canine calcium oxalate urolithiasis

Calcium oxalate uroliths are commonly called metabolic uroliths because they are sequelae of a variety of metabolic abnormalities that alter the composition of body fluids and urine. Factors incriminated in the etiopathogenesis of calcium oxalate urolithiasis include hypercalciuria, hyperoxaluria, and hyperuricosuria. The predominant type of calcium oxalate urolith encountered in dogs is the monohydrate form; however, the dihydrate form may also occur. Male dogs have been more frequently affected than female dogs. Medical therapy should be formulated with the goal of reducing urine concentration of calculogenic substances.     

Hypertension: A review of the mechanisms, manifestations and management

Hypertension is a common disease of man although it is rarely diagnosed in veterinary medicine. This partly reflects a failure of recognition of the incidence and importance of hypertension in animals. Recognition of hypertension is usually late in the course following acute ocular, cardiac, renal or neurological presentation. Early screening and identification of hypertension is important as it is an organ destructive and self-perpetuating process. The physiological control and measurement of blood pressure and the pathogenesis and management of hypertension in small animals is reviewed.     

Effects of body condition and supplementation on ovarian function,growth factors and response to estrus synchronization in postpartum beef cows in Tamaulipas,Mexico

ABSTRACT

Eighteen beef cows with their calves were assigned to 3 groups considering body conditions scores at calving (BCSC): T1 (high BCSC, maintained throughout the study); T2 (low BCSC, increased during the study); and T3 (low BCSC, maintained throughout). An estrus synchronization protocol was implemented, with fixed time artificial insemination on day 70. Follicular or luteal growth, and pregnancy rate were similar between groups. Of all cows, five showed multiple ovulations (2–6); increasing number of ovulations reduced preovulatory follicle diameter and individual luteal volume (P?<?0.05), but total luteal volume was greater in cows with 2 or 3 ovulations on day 14 after insemination (P?<?0.05). Estradiol and progesterone levels were associated to follicular and luteal growth, respectively. No difference was found in IGF1 or GDF9 levels between groups or associated to fertility. No association was found between BCS, IGF1 or GDF9 levels and the reproductive process.