Mineral requirements of hair sheep in tropical climates

In this study, we evaluated the requirements of calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na) and potassium (K) for sheep hair growth. Experimental diets contained different levels of metabolizable energy [ME; 0.96, 1.28, 1.72, 2.18 and 2.62 Mcal/kg of dry matter, (DM), corresponding to 4.23, 5.64, 7.58, 9.61 and 11.55 MJ/kg DM]. The lambs' hair (n = 48) at 2 months of age presented an average body weight (BW) of 12.05 ± 1.81 kg. At the beginning of the experiment, eight animals were slaughtered as a reference group to estimate the initial empty body weight and body composition. Net mineral requirements (g/day) ranged from 0.73 to 0.71 g of Ca, 0.51 to 0.49 g of P, 0.026 to 0.026 g of Mg, 0.16 to 0.19 g of Na and 0.15 to 0.13 g of K for animals with a BW ranging from 15 to 30 kg and a daily gain of 100 g. The results of this study indicate that the net macromineral requirements for weight gain in Morada Nova lambs are different from the values commonly recommended by the Agricultural and Food Research Council.     

Retinol, β-carotene and β-tocopherol concentrations in mare and foal plasma and in colostrum

Fat-soluble vitamins transfer poorly across the diffuse epitheliochorial placenta of the mare, so the neonatal foal is dependent on its supply via colostrum. Concentrations of retinol (RT), β-carotene (BC), and β-tocopherol (AT) were assayed in samples of plasma, colostrum and milk from nine mares of mixed light breeding and their foals at parturition and days 1, 2, and 4 postpartum. Samples were analyzed simultaneously for RT, BC, and AT using a new, less time-consuming reverse phase high-pressure liquid chromatography (HPLC) method. Feeds were analyzed, and mean daily intakes calculated. Mare plasma RT increased from day 1 to day 4 (P = .033), and plasma AT declined linearly from day 0 to day 4 (P = .006). Colostrum concentrations of all vitamins increased from parturition to day 1, and then declined rapidly over the 4 days. Foal plasma BC increased from parturition to day 4 (P = .080), and plasma AT increased from parturition to day 2 (P < .001), and 4 (P = .060). These observations suggest that three times the current recommendation of vitamin A is sufficient for pregnant mares, in keeping with previous studies of growth, pregnancy, and lactation. In contrast, the linear decrease in mare plasma AT suggests that 1.2 times the current recommendation of vitamin E may be less than optimal for pregnant mares.

Introduction

The diffuse epitheliochorial placenta of the mare does not allow fat-soluble vitamins to cross with ease to the fetus,[1] so their status in the neonatal foal is dependent on colostrum. This first milk contains these vitamins, which are necessary for many functions.Vitamin A is required for vision, reproduction, growth, development, and maintenance of epithelial cells, and osteoclast activity in bone formation. In addition, vitamin A deficiencies reduce resistance to disease, can cause neurological degeneration, and congenital defects.[2] Vitamin E, an antioxidant, prevents lipid peroxidation and cell membrane damage. Its deficiency in horses has been associated with a form of muscular dystrophy and impaired immune function. [3]Studies on the mare and foal have described blood concentrations of one or two of these vitamins,[4, 5 and 6] but only one involved all three. [7] In that study, vitamin concentrations were assayed in mare blood and milk, but only once in foal blood at parturition, so data during the periparturant period is incomplete.The objectives of this enumerative study were to determine concentrations of RT, BC, AT in plasma and colostrum, to evaluate colostral transfer of these vitamins, to assess the adequacy of vitamin intakes of mares, and to develop a time-saving single-run HPLC method.

Materials and methods

Animals

Nine healthy aged multiparous mares of mixed light breeding (13.6 ± 1.5 years, 592 ± 20 kg body mass) and their foals were sampled. The institutional animal care and use committee approved the protocol. Mares were kept on meager late-winter mixed grass pasture, with free access to round bale orchard and fescue grass hay, water, and trace mineral/vitamin salt. They were fed 2 kg of concentrate twice daily at 7:00 and 3:00 . The diet met or exceeded current recommendations for pregnant mares at 11 months gestation for energy.[8] Samples of hay and concentrate were submitted for partial proximate analysis to the Virginia Tech Forage Testing Laboratory where standard AOAC [9] methods are used ( Table 1). Samples of feeds were also taken for analysis of RT, BC, and AT ( Table 2).     

Effects of dietary lysine and energy density on performance and carcass characteristics of finishing pigs fed ractopamine

Two hundred sixteen crossbred barrows and gilts (84.3 kg BW) were used to test the effects of dietary energy density and lysine:energy ratio (Lys:ME) on the performance, carcass characteristics, and pork quality of finishing pigs fed 10 ppm ractopamine. Pigs were blocked by BW and gender, allotted to 36 pens (six pigs per pen), and pens were assigned randomly within blocks to dietary treatments (as-fed basis) arranged in a 2 x 3 factorial design, with two levels of energy (3.30 or 3.48 Mcal/kg) and three Lys:ME (1.7, 2.4, or 3.1 g lysine/Mcal) levels. Pigs were fed experimental diets for 28 d, and weights and feed disappearance were recorded weekly to calculate ADG, ADFI, and G:F. Upon completion of the feeding trial, pigs were slaughtered and carcass data were collected before fabrication. During carcass fabrication, hams were analyzed for lean composition using a ham electrical conductivity (TOBEC) unit, and loins were collected, vacuum-packaged, and boxed for pork quality data collection. Energy density had no (P > 0.22) effect on ADG or ADFI across the entire 28-d feeding trial; however, pigs fed 3.48 Mcal of ME were more (P < 0.02) efficient than pigs fed 3.30 Mcal of ME. In addition, ADG and G:F increased linearly (P < 0.01) as Lys:ME increased from 1.7 to 3.1 g/Mcal. Carcasses of pigs fed 3.48 Mcal of ME were fatter at the last lumbar vertebrae (P < 0.08) and 10th rib (P < 0.04), resulting in a lower (P < 0.03) predicted fat-free lean yield (FFLY). Conversely, 10th-rib fat thickness decreased linearly (P = 0.02), and LM depth (P < 0.01) and area (P < 0.01) increased linearly, with increasing Lys:ME. Moreover, FFLY (P < 0.01) and actual ham lean yield (P < 0.01) increased as Lys:ME increased in the diet. Dietary energy density had no (P > 0.19) effect on pork quality, and Lys:ME did not (P > 0.20) affect muscle pH, drip loss, color, and firmness scores. Marbling scores, as well as LM lipid content, decreased linearly (P < 0.01) as Lys:ME increased from 1.7 to 3.1 g/Mcal. There was a linear (P < 0.01) increase in shear force of cooked LM chops as Lys:ME increased in the finishing diet. Results indicate that 3.30 Mcal of ME/kg (as-fed basis) is sufficient for optimal performance and carcass leanness in pigs fed ractopamine. The Lys:ME for optimal performance and carcass composition seems higher than that currently used in the swine industry; however, feeding very high Lys:ME (> 3.0 g/Mcal, as-fed basis) to ractopamine-fed pigs may result in decreased marbling and cooked pork tenderness.     

Chronic canine ehrlichiosis (Ehrlichia canis): a retrospective study of 19 natural cases

Nineteen dogs from Greece with chronic ehrlichiosis were studied. The dogs exhibited bicytopenia or pancytopenia, bone marrow hypoplasia, seroreactivity to Ehrlichia canis (E. canis) antigens, and had no history of drug or radiation exposure. Anorexia, depression, severe bleeding tendencies, hypoalbuminemia, and increased serum alanine aminotransferase activity were also hallmarks of the disease. All these animals eventually died, irrespective of the treatment applied. Some dogs were also serologically positive for Rickettsia conorii, Leishmania infantum (L. infantum), and Bartonella vinsonii subspp. berkhoffii. Polymerase chain reaction testing of bone marrow samples revealed E. canis, Anaplasma phagocytophilia, Anaplasma platys, and L. infantum in some dogs. Concurrent infections did not appear to substantially influence the clinical course and final outcome of the chronic canine ehrlichiosis.     

The use of a genetic-counselling program by Dutch breeders for four hereditary health problems in boxer dogs

Our group developed a genetic-counselling program for boxer-dog breeders in The Netherlands, using data for cryptorchidism (uni- and/or bilateral), epilepsy, knee-problems (including ligament rupture, fractured or ruptured meniscus, severe osteo-arthrosis of the knee, or a combination of these disorders), and schisis (including cheiloschisis, palatoschisis, or cheilopalatoschisis). We transformed the estimated breeding values (EBVs) into odds ratios (ORs), to enable the breeder to compare the risk for each of the traits for a certain dam-sire combination with the average population risk (set at 1). The goal of the study was to evaluate the use of our genetic-counselling program by Dutch breeders of boxer dogs. We asked breeders of the Dutch Boxer Club to send in an application form for genetic-counselling from June 1 to December 1, 2000. Breeders indicated on this application form three desirable sires for their dam (sire 1, sire 2, sire 3) in random order. On the basis of this information, a counselling report was produced which included ORs for the four diseases in litters of the dam-sire combinations indicated on the application form. Together with the counselling report, the breeders received an evaluation form. We received 129 application forms from 70 breeders, and collected 125 evaluations. Of these evaluations, 96 were informative about the influence of the counselling report on sire choice. The most-important criteria used by breeders to select sires were: the exterior characteristics (60%) and known progeny (52%). Although it was the first time breeders could make use of genetic-counselling, 32% of the breeders indicated that the genetic-counselling played a major role in their sire selection. Breeders expressed little difference in importance for the four genetic traits, but there was a tendency to consider epilepsy more than the others. Breeders hesitated to put long-term population interest above short-term personal interest. Nevertheless, the general conclusion of this study is that breeders acknowledge the value of counselling, especially to reduce the frequency of a threatening disease such as epilepsy.     

Influenza surveillance in birds in Italian wetlands (1992-1998): is there a host restricted circulation of influenza viruses in sympatric ducks and coots?

We report the results of a 6-year serological and virological monitoring performed in ducks and coots in Italy, in order to assess the degree of influenza A virus circulation in these birds during wintering. A total of 1039 sera collected from 1992 to 1998 was screened by a double antibody sandwich blocking ELISA (NP-ELISA): seroprevalence of antibodies to influenza A viruses was significantly higher in ducks compared to coots (52.2% vs. 7.1%, respectively). The hemagglutination-inhibition (HI) assay, performed on NP-ELISA positive sera, showed that 16.9% of these duck sera and 33.3% of these coot sera had antibodies to at least one influenza virus HA subtype: ducks showed HI antibodies against most of the HA subtypes, except for the H3, H4, H7, and H12; coots were seropositive to the H3 and H10 subtypes, only. From 1993 to 1998, 22 virus strains were obtained from 802 cloacal swabs, with an overall virus isolation frequency of 2.7%. Viruses belonging to the H1N1 subtype were by far the most commonly circulating strains (18/22) and were isolated mainly from ducks (17/18). The remaining viruses were representative of the H10N8, H5N2 and H3N8 subtypes. Our data indicate some differences between influenza A virus circulation in sympatric ducks and coots and a significant antigenic diversity between some reference strains and viruses recently isolated in Italy.