Current approaches to the management of ovine footrot

Ovine footrot remains the most important cause of lameness in sheep flocks in the UK, despite the existence of proven methods for the control of the disease. Recent research suggests that sheep farmers may be unaware of these methods and may allocate greater resources to treatment of footrot rather than to its prevention. Foot paring, topical treatments, vaccination and parenteral antibiotic therapy all have a role in treating sheep with advanced footrot infections, but prevention of severe infections is best achieved by the timely implementation of control programmes. These are usually based on footbathing and vaccination. For control programmes to be effective it is essential that the pathogenesis and epidemiology of footrot is understood and that control methods are implemented at appropriate times in the season, depending on climatic and pasture conditions. This article reviews these strategies and makes recommendations for steps to reduce the spread of footrot between flocks and to reduce the incidence of footrot within UK flocks.     

Effect of exogenous oestradiol and lighting regime on age at first egg in domestic pullets

1. Groups of ISA Brown pullets were transferred from 8- to 16-h photoperiods at 34, 44 or 54 d. In each group, 12 birds were injected on alternate days over a 12-d period starting 6 d before the change in photoperiod with beta-oestradiol-3-benzoate (1 mg/kg body weight) or with arachis oil vehicle (controls). Short-day controls were similarly injected from 28 to 40 d. Long-day (16 h) controls were also included in the trial but were not injected. Age at first egg (AFE) was recorded and plasma luteinising hormone (LH) concentrations were measured around the time of oestradiol treatment. 2. Mean AFE for birds photostimulated at 34 d was not significantly different from short-day controls. Birds photostimulated at 44 and 54 d matured at similar ages but 3 weeks earlier than short-day controls (P<0.05). 3. There was a tendency for oestradiol to advance AFE for birds photostimulated at 34 d (P=0.15) but to delay AFE following photostimulation at 44 d (P=0.23). Oestradiol significantly delayed AFE for the birds photostimulated at 54 d (P=0.01). 4. Plasma LH levels during 6 d of oestradiol injection but before transfer from 8- to 16-h photoperiods tended to fall between 28 and 34 d, were relatively constant between 38 and 44 d, but declined significantly between 48 and 54 d. Following photostimulation at 34 d, increases in plasma LH levels for oestradiol-injected birds were significantly greater than for controls. Oestradiol treatment had no significant effect on changes in plasma LH concentrations after photostimulation at 44 or 54 d. 5. This trial confirms previous work showing that pullets are unresponsive to photostimulation before 6 weeks of age. It also demonstrates that raising circulating oestrogen levels by injecting 0.5 mg/kg oestradiol benzoate on alternate days enhances the LH response to photostimulation at 34-d, but only very slightly sensitises a 34-d old bird to an increase in photoperiod which, 10 d later, is capable of advancing AFE in control birds by 24 d. Increased circulating oestrogen might be a factor which allows pullets to advance AFE in response to an increase in daylength.     

Gross anatomical and histomorphometric characteristics of the oviduct and uterus during the pubertal transition in sheep

Gross anatomical and histometric characteristics of oviducts and uteri were evaluated during the pubertal transition in ewe lambs. Lambs were hysterectomized prepubertally (PP; n = 10) or 26 +/- 2 h after onset of first (FE; n = 13) or third estrus (TE; n = 12), or estrus in mature pluriparous ewes (ME; n = 4). Gross characteristics included diameters, lengths, and weights of oviducts; diameters of uterine cornua; and weights of uteri. Histometric characteristics of ampullae, isthmi, and uterine cornua included epithelial cell volume, total luminal surface area, and total number of cells per ampulla or isthmus and area of the muscularis. Side of the reproductive tract did not affect (P > 0.10) any gross or histometric characteristic. Gross uterine characteristics increased (P < 0.05) dramatically between PP ewes and FE ewes, and then increased (P < 0.05) to a lesser degree between FE and TE ewes, and again (P < 0.05) between TE and ME ewes. Histological characteristics of uteri followed a similar developmental pattern: large changes (P < 0.05) between PP and FE ewes, slight increases between FE and TE ewes, and no change (P > 0.10) between TE and ME ewes. Oviductal weight and length showed little change (P > 0.10) at puberty or by third estrus, but they were greater (P < 0.05) in ME ewes than in the other groups. The diameters of ampullae increased (P < 0.05) at puberty, showed no change between FE and TE ewes, and were greatest (P < 0.05) in mature ewes. These changes seemed to be due to increases (P < 0.05) in mucosal cell height and muscularis area at puberty, and to muscularis area and submucosal thickness between TE and ME ewes. The surface area of the ampullae increased (P < 0.05) at puberty or by third estrus in a linear manner between PP, FE, TE, and ME ewes. The diameters of isthmi did not change (P > 0.10) at puberty but increased (P < 0.05) between FE and TE, and were greatest (P < 0.05) in ME ewes. The histological characteristics of isthmi followed the pattern observed in the ampullae. However, the surface area of the isthmi showed no change (P > 0.10) at puberty or by third estrus and was largest (P < 0.05) in ME ewes. Results of this study indicate that gross morphological characteristics of uteri and oviducts increase at puberty with either slight increases or changes after two estrous cycles. This relationship is also reflected by histological characteristics of these organs during the pubertal transition of sheep.     

Reproductive response of ewes to immunization with Fecundin (ovandrotone)

Ewes of five crossbred genotypes (total of 221 ewes) were immunized with a commercial preparation of androstenedione-7HSA in DEAE dextran adjuvant in a 2-yr trial. In yr 1 ewes were allocated within genotype to a 2 x 2 application of immunization and premating flushing. In yr 2 they were allocated within previous Fecundin treatment into either Fecundin-treated or control groups. First-time immunization with Fecundin increased ovulation rate by .70 ova/ewe in yr 1 and by .85 ova/ewe in yr 2 (P less than .05). Ewes treated in both years produced fewer ova than those treated in the 2nd yr only (P less than .05), but they did not differ in litter size. Although Fecundin reduced conception to first mating, the overall conception rate was not affected. Litter size of treated ewes was increased by .19 and .38 lambs/ewe lambing (P less than .05) in yr 1 and yr 2, respectively. Fecundin treatment in yr 1 produced a carry-over effect in yr 2 by increasing litter size by .26 lamb/ewe (P less than .05) while reducing conception to first mating. The litter size of ewes with two ovulations was reduced by Fecundin treatment in yr 1 (P less than .05) but showed no consistent pattern in yr 2. Overall, ewes with two ovulations produced .7 to .8 more lambs than ewes with one ovulation, and ewes with three ovulations produced .4 more lambs than those with two ovulations. Ewes of different genotypes did not differ in their response to Fecundin.     

Effect of alpha-tocopheryl acetate supplementation on vitamin E concentrations in Greyhounds before and after a race.

OBJECTIVES: To determine effect of alpha-tocopherol supplementation on serum vitamin E concentrations in Greyhounds before and after a race. ANIMALS: 8 adult racing Greyhounds. PROCEDURE: Dogs were given 2 capsules of alpha-tocopheryl acetate (total, 680 units [0.5 g]) with food that contained < or = 15 mg of vitamin E/kg each morning for 7 days. Dogs were exercised in a 30 X 30-m grass paddock for 15 minutes twice a day and raced for 500 m twice a week. Blood samples were collected before and 5 minutes after a race, before supplementation was begun, and after 7 days of supplementation. Blood and diet samples were analyzed for tocopherols and alpha-tocopheryl acetate. RESULTS: Before supplementation, serum alpha-tocopherol concentration after racing (mean +/- SD, 6.7 +/- 2.4 mg/L ) was significantly lower than before racing (12.2 +/- 3.1 mg/L). After supplementation, alpha-tocopherol concentrations were significantly higher overall, although values obtained before (26.6 +/- 5.2 mg/L) and after (29.8 +/- 3.6 mg/L) racing were not significantly different. CONCLUSIONS AND CLINICAL RELEVANCE: Supplementation with alpha-tocopheryl acetate increased serum alpha-tocopherol concentrations and eliminated the decrease in alpha-tocopherol concentration that was detected after a race, which may decrease oxidation during exercise and improve performance or recovery.     

Cervical spondylomyelopathy ('wobbler' syndrome) in the dog: A study based on 224 cases

Over the past 10 to 12 years, cervical spondylomyelopathy has been increasingly recognised in large breed dogs. The breeds mainly affected are dobermanns, great danes and basset hounds. Factors such as age, sex and location of the lesions are discussed in detail based on findings from 224 cases seen at the University of Liverpool Small Animal Hospital. The anatomical changes responsible for the signs show some striking similarities in young dogs of all the breeds affected. Where the condition is commoner later in life, such as in the dobermann, the changes and their effect on the spinal cord show considerable differences. These different findings are compared, and an attempt made to explain them.     

Effect of dietary fluorine on growth, blood and bone characteristics of growing-finishing pigs

Three hundred eighty-four growing-finishing pigs were used in two experiments to determine the effect of dietary fluorine (F) on growth, blood and bone physical characteristics. Fourteen dietary treatments were formulated by supplementing F (as NaF) to a milo-soybean meal basal diet (7 ppm F) to provide levels of 7, 132, 257, 382, 507 and 632 ppm F for Exp. 1, and 7, 25, 43, 61, 79, 97, 115 and 133 ppm F for Exp. 2. Average daily gain (ADG) and average daily feed intake (ADFI) were not affected (P greater than .09) when F was fed at levels between 7 and approximately 132 ppm. Average daily gain and ADFI were reduced (P less than .0001) for pigs consuming diets with F concentrations greater than 132 ppm (Exp. 1). Feed conversion was not affected (P greater than .17) by any level of F fed. Serum F and alkaline phosphatase concentrations increased (P less than .01) with increasing dietary F levels. Serum and bone Ca and P concentrations were not affected (P greater than .13) by dietary F levels (Exp. 1). In Exp. 1 and 2, bone F increased (P less than .0001) and metatarsal stress and modulus of elasticity decreased (P less than .0001) as level of F increased in the diet. Bone thickness decreased quadratically (P less than .02) in Exp. 1 and linearly (P less than .0007) in Exp. 2 with increased dietary F levels. Scanning electron microscopy showed an increase in porosity of bones from pigs fed the higher levels of F. Growing-finishing pigs were able to tolerate approximately 132 ppm F for growth, but all of the F levels (greater than or equal to 7 ppm) fed in these two experiments affected bone integrity.