Interactions between dietary crude protein and essential amino acid intake on performance in broilers

1. The effect of diets with increasing concentrations of crude protein at either fixed essential amino acid concentrations or at fixed essential amino acid:dietary crude protein ratios on performance was examined in 1- to 4-week-old male Cobb chicks. Increasing crude protein intakes at constant essential amino acid concentrations was carried out at two dietary energy contents. 2. Increasing crude protein resulted in a linear decrease in feed intake while weight gain and feed efficiency changed quadratically with a smaller positive effect at the highest crude protein intakes. Feed intake decreased and feed efficiency increased with higher dietary energy and interactions between protein and energy were significant. Abdominal fat content and the efficiency of protein retention decreased with increasing dietary protein intake. 3. Using constant essential amino acid:crude protein ratios at increasing crude protein intakes resulted in (Trial 3) feed intake, weight gain and feed efficiency all increasing before reaching a plateau. Abdominal fat decreased with protein intake and the efficiency of protein retention was quadratic, decreasing at the higher protein intakes. 4. Multiple regression analysis of the results of the three trials indicated that partition of energy intake into maintenance, fat-free tissue growth, fat and the energy required to transform protein intake in excess of retention explained more than 98% of variation. 5. It is proposed that broiler performance at the lower protein intakes was limited by either non-essential amino acid (Trials 1 and 2) or essential amino acid (Trial 3) intake whereas at high protein intakes the decreased efficiency of amino acid utilisation after growth requirements are fulfilled resulted in poorer performance.     

Genetic resistance to Salmonella typhimurium in two lines of chickens selected as resistant and sensitive on the basis of heterophil/lymphocyte ratio

1. A study was conducted to test for the validity of the heterophil/lymphocyte (H/L) ratio as a criterion for selection for resistance to Salmonella typhimurium in chickens. 2. An infective dose of S. typhimurium was given, directly in the crop, to two groups of chicken selected as Resistant (R) and Sensitive (S) on the bases of H/L ratio. The 99% lower confidence limit was used as a borderline; individuals below the limit were considered R and those above S. Many aspects of immune response were compared, namely: H/L ratio, antibody titre, cellular immunity, phagocytic activity, cortisol concentration, bursa and body weight. 3. The R group exceeded the S in all the studied variables of the immune response, indicating the possibility of using the H/L ratio and its confidence limit to select for general resistance. 4. Due to the within-strain variability in resistance, it seems that immunological and genetic studies should take into consideration separation of individuals into R and S before grouping. Failing to do so might lead to erroneous conclusions as a difference may simply be due to the different numbers of R and S included in each group.     

Effects of restricted feeding on physiological stress parameters in growing broiler breeders

1. In previous studies, a lack of agreement in measurements of plasma corticosterone concentrations and heterophil:lymphocyte (H/L) ratio as physiological indices of stress, caused by hunger and frustration in restricted-fed broiler breeders, was observed. It could be suggested that the differences between previous studies were caused by differences in duration of restriction and time of the day of the measurements. Therefore, in the present study the plasma corticosterone concentration and the H/L ratio were again determined in restricted- and ad libitum-fed growing broiler breeders, taking possible causes of disagreement between previous studies into account. In addition, we measured the daily rhythm in body temperature and heart rate, and the corticosterone responses to an acute stressor as physiological indices of stress. 2. Female broiler breeders (64 per treatment, housed in groups of 4 birds) were used in the experiment. Behaviour, baseline plasma corticosterone concentrations and H/L ratio were determined at 21 d of age (immediately after the start of food restriction), and at 42 and 63 d of age. Body temperature, heart rate and activity were measured by radiotelemetry for 36 h at 49 and 70 d of age. In addition, the plasma corticosterone response to acute stress (5 min manual restraint) was measured at 77 or 78 d of age. 3. Restricted broiler breeders had higher plasma corticosterone concentrations at 42 and 63 d of age, but no differences in H/L. ratio were found between restricted birds and unrestricted control birds. Restricted broiler breeders had a higher corticosterone response to 5 min manual restraint than unrestricted birds. Restricted birds displayed a clear day-night rhythm in body temperature, heart rate and activity whereas such a rhythm was blunted in ad libitum-fed birds. 4. It is discussed that some physiological differences (plasma corticosterone concentrations, body temperature and heart rate) between ad libitum-fed and restricted broiler breeders may have been caused by differences in metabolic rate as well as by differences in the level of stress. It is concluded that a combination of behavioural measurements and a wide range of physiological parameters should be used for the assessment of stress in growing broiler breeders.     

Diagnosis by polymerase chain reaction of Erysipelas septicemia in a flock of ring-necked pheasants

A flock of 810 pheasants experienced 6.2% mortality over 6 days. Affected birds were weak and lethargic for up to 24 hr before death. Examined birds were thin, and gross lesions consisted of thick opaque crops and cecal cores. Histologically, there was capillariasis of the crop and multifocal ulcerative typhlitis with Heterakis spp. infection, and numerous systemic intravascular monocytes were filled with clusters of blue rod-shaped organisms. The organisms were gram-positive bacilli by Brown and Brenn staining and ultrastructural analysis. Liver bacterial cultures were negative for pathogenic bacteria. Erysipelas septicemia was diagnosed by an Erysipelothrix species-specific polymerase chain reaction method with the substrate DNA isolated from formalin-fixed, paraffin-embedded liver.     

Primary glaucoma in Burmese cats

OBJECTIVE: To document the clinical signs and management of primary glaucoma in Burmese cats. DESIGN: A retrospective study of six affected Burmese cats, from 1996 to 2001. Procedure Six Burmese cats diagnosed with primary glaucoma were managed over periods varying from 3 months to 4.5 years. Clinical details were obtained from practice records. Gonioscopic examination of the drainage or iridocorneal angle in eyes of these affected cats was made. RESULTS: Six desexed female Burmese cats (ages 7.0 to 10.5 years) presented with complaints of either unilateral (n = 4) or bilateral (n = 2) red eye, dilated pupil or enlarged eye. In one of the affected cats, one eye had been enucleated prior to the commencement of the study, thus a total of 11 eyes were examined. Clinically, all affected eyes (n = 8) had injected episcleral blood vessels and elevated intraocular pressure. Gonioscopy revealed the presence of nine narrow and two closed iridocorneal angles. Medical therapy included topical 2% dorzolamide (n = 8), 0.5% timolol maleate (n = 1), 0.005% latanoprost (n = 1) and 0.5-1.0% prednisolone acetate (n = 8). Surgery was performed in six eyes using either diode laser (n = 5) and/or cryothermy (n = 2) and one eye was eviscerated, with implantation of a prosthesis. With therapy, five affected eyes maintained vision and normal intraocular pressure, one eye remained blind with normal intraocular pressure, one eye remained blind with elevated intraocular pressure and one eye was eviscerated. CONCLUSIONS: The Burmese cat may be predisposed to primary narrow-angle glaucoma. Early diagnosis and continuous antiglaucoma therapy can help control intraocular pressure and maintain vision.     

Neuronal ceroid lipofuscinosis in Merino sheep

OBJECTIVE: To characterise neuronal ceroid lipofuscinosis (NCL) in Merino sheep. DESIGN: A prospective clinical, pathological, biochemical and genetic study. PROCEDURE: NCL cases were studied from a medium-wool Merino flock, the stud of origin of its replacement rams, and an experimental flock established at the University of Sydney. RESULTS: Behavioural changes and visual impairment were first detected at 7 to 12 months of age and progressed, with associated motor disturbances and at later stages seizures, to premature death by 27 months of age. At necropsy there was severe cerebrocortical atrophy associated with neuronal loss, astrocytosis and the presence in neurons of eosinophilic intracytoplasmic storage bodies with the characteristics of a lipopigment. In the retina there was progressive loss of photoreceptor cells. Storage bodies isolated from fresh brain, liver and pancreas formed electron-dense aggregates and coarse multilamellar and fine fingerprint profiles ultrastructurally, and consisted mainly of the hydrophobic protein, subunit c of mitochondrial ATP synthase. A homozygosity mapping approach localised the gene causing the disease in Merino sheep to the chromosomal region (OAR7q13-15) associated with NCL in South Hampshire sheep. CONCLUSION: NCL in Merino sheep is a subunit c-storing disease, clinically and pathologically similar to NCL in South Hampshire sheep. We propose that the disease in both breeds represents mutation at the same gene locus in chromosomal region OAR7q13-15.     

The nutritional value of degermed,dehulled corn for pigs and its impact on the gastrointestinal tract and nutrient excretion

Three experiments were designed to assess the feeding value and potential environmental benefits of feeding degermed, dehulled corn, a low fiber by-product originating from the corn dry milling process, to pigs. Twelve 27-kg (SE = 0.8) barrows were used in Exp. 1 to measure the apparent fecal digestibility of DM, GE and N of degermed, dehulled corn compared with corn grain. Two diets were formulated to contain either 96.4% of degermed, dehulled corn or corn grain plus supplemental vitamins and minerals. Digestibilities of DM, GE, and N were greater in degermed, dehulled corn (96.2, 96.0, and 93.6%, respectively) compared with corn grain (89.0, 89.0, and 78.4%, respectively) (P < 0.01). Overall, a 67 and 29% reduction in DM and N excretion, respectively, was observed. In Exp. 2, eight 70-kg (SE =1.8) barrows were surgically fitted with ileal cannulae and fed the same diets as in Exp. 1, to measure the ileal digestibility of nutrients in degermed, dehulled corn. Ileal digestibility of DM, energy, and N was 13, 15, and 7% greater in degermed, dehulled corn (P < 0.05). Apparent ileal digestibility coefficients of leucine, methionine, and phenylalanine were greater in degermed, dehulled corn compared with corn grain (P < 0.05) while a trend for a lower tryptophan digestibility in degermed, dehulled corn was observed (P = 0.067). In Experiment 3, 96 nursery pigs with an initial average BW of 8.8 kg (SE = 0.08), fed a starter diet formulated with degermed, dehulled corn or corn grain as the major grain source, were used in a 28-d growth performance study. At the end of the study, 24 pigs (1 pig per pen) were sacrificed and gastrointestinal tract measurements were taken. Daily growth rates of pigs were the same between diets (0.64 kg/d). A trend for reduced feed intake (P = 0.073) in pigs fed degermed, dehulled corn led to a 4% improvement in gain to feed (P < 0.05). Feeding degermed, dehulled corn had no effect on gut fill, gastrointestinal tract weight, or liver weight (P > 0.05). Ileal villus lengths and crypt depths were not affected by feeding degermed, dehulled corn although ileal villus widths were greater in pigs fed corn grain. Results from these trials suggest that corn processed to remove poorly digestible fiber fractions provides more digestible nutrients than corn grain. As a result, degermed, dehulled corn reduces fecal and N excretion, thus providing a means to reduce nutrient excretion.     

Gamma herpesvirus carrier status of captive artiodactyls

Between 1998 and 2000, 103 individuals of 19 species of the order Artiodactyla at Whipsnade Wild Animal Park were tested for evidence of infection with gamma herpesviruses in order to distinguish between species which are susceptible to malignant catarrhal fever (MCF), caused by alcelaphine herpesvirus-1 (AlHV-1) of wildebeest (Connochaetes sp.) or ovine herpesvirus-2 (OvHV-2) of domestic sheep, and species which carry related viruses sub-clinically. Gamma herpesvirus DNA was detected in the known, or suspected, carrier species: roan antelope (Hippotragus equinus), scimitar-horned oryx (Oryx dammah), gemsbok (Oryx gazella), musk ox (Ovibos muschatus) and mouflon (Ovis musimon). In six other species: lowland anoa (Bubalus depressicornis) yak (Bos grunniens), sitatunga (Tragelaphus spekei), greater kudu (Tragelaphus strepsiceros), waterbuck (Kobus ellipsiprymnus) and Nile lechwe (Kobus megaceros), DNA was present in some newborn calves and over 30% of adults, strongly suggesting a carrier state. In contrast five Père David's deer (Elaphurus davidianus) and two swamp deer (Cervus duvauceli) died of MCF during the study. A virus isolated from scimitar-horned oryx calves produced cytopathic effects in scimitar-horned oryx kidney cell-culture and caused MCF in a rabbit.