Effect of dietary protein content on live and carcase performance of heterozygous naked neck and normally feathered broilers

1. An experiment was conducted to determine the effect of different dietary protein contents on the performance of naked neck (Na/na) and normally feathered (na/na) broilers.

2. Chicks from the two genotypes were reared in wire‐floored cages and divided at random into 3 groups. Birds were fed on high protein (HP, 12.99 MJ ME, 238 g crude protein/kg and 12.94 MJ ME, 216 g crude protein/kg from 0 to 3 and 3 to 7 weeks, respectively), medium protein (MP, 12.99 MJ ME, 219 g crude protein/kg and 12.87 MJ ME, 201 g crude protein/kg from 0 to 3 and 3 to 7 weeks), and low protein (LP, 12.94 MJ ME, 205 g crude protein/kg and 12.75 MJ ME, 184 g protein/kg from 0 to 3 and 3 to 7 weeks) diets.

3. The LP diets resulted in a significantly lower daily body weight gain of males from 0 to 3 weeks. Dietary protein content had no effect on body weight gain from 3 to 7 weeks, body weight at 7 weeks, and the food intake of birds. Carcase composition of birds from both genotypes was unaffected by dietary protein.

4. Naked neck birds had significandy higher body weights at 7 weeks. Yields of carcase and breast of Na/na males were significantly higher than those of na/na males. There were no significant differences between females from the two genotypes as regards carcase yield.

5. It was concluded that the dietary protein requirements of naked neck birds were similar to those for normally feathered birds.     

Seroprevalence of Brucella ovis infection in commercial ram flocks in the Tamworth area

Commercial ram flocks in the Tamworth area of northern New South Wales were surveyed to estimate the proportion of flocks, and rams, infected with Brucella ovis. The flock prevalence (percentage of flocks containing seropositive rams) of 9.1% for Merino flocks was significantly lower than that for British-breed flocks (43.8%, p=0.006) and mixed-breed flocks (46.7%, p=0.017). The mean flock prevalence over all flock types was 32.9%. These estimates were supported by data obtained from diagnostic testing for brucellosis carried out during the previous 6 years. The seroprevalence in rams was 10.8% overall, 2.5% for Merinos, 19% for Border Leicester and 26% for Dorset rams. Within infected flocks, the estimated prevalences were 21%, 65% and 67% for Merinos, Border Leicester and Dorset rams respectively. The seroprevalence in Merino rams was significantly lower than that for both other breeds (p<0.001) for all flocks and in infected flocks. There was no apparent association between age and serological status, or age and the prevalence of epididymitis.     

Chylous effusions revisited

Varying terms and criteria have been used in the veterinary literature to characterize milky opaque pleural effusions through the years. This article addresses ideas widely repeated in the veterinary and human literature upon which time, experience, diagnostic techniques, experimental data, and improved understanding of pathogenesis have cast doubt. Topics discussed include terminology, pathogenesis of chylous and pseudochylous effusions, criteria for differentiation of chylous from pseudochylous effusions, and clinicopathologic changes associated with drainage of chylous effusions.     

Comparison of the rates of proliferation of adipocyte precursor cells derived from two lines of chicken which differ in their rates of adipose tissue development

1. Putative adipocyte precursor cells were isolated from the white adipose tissue of young broiler and layer chickens and cultured in vitro.

2. The cells from both sources were shown to have the characteristics of adipocyte precursor cells. On reaching confluence, lipoprotein lipase activity was induced and the cells from both strains accumulated large amounts of lipid in the presence of chicken serum.

3. Measurement of cell number over time in culture and calculation of cell doubling times showed that cells from broilers proliferated at a faster rate than those derived from layer‐strain chickens. This was the case whether primary or secondary cell cultures were used. Primary cultures of broiler cells had a doubling time of 22 h versus 39 h for layer cells.

4. The contribution of such a difference in proliferative rate to the differential rate of adipose tissue growth between broiler and layer strains observed in vivo is discussed.     

Comparison of alternative methods of handling contemporary group effects in animal model prediction

SUMMARY: Methods to associate animals between periods (grouping of records within a calving season into a 60-day interval starting from the date of the first calf born for 400-day weight analysis) within the contemporary group classification on sexmanagement group-date of weighing, using an animal model were compared. The data were derived from ten Angus herds. Assigning animals to more than one period and/or treating period as random or introducing days from start of calving period as a co-variate (linear and quadratic) did little to improve herd mean square error compared to the basic model where there were no associations between periods. The reduction in the standard errors of predictions were significant (p < 0.05) only when period within sex-management group-date of weighing was treated as random. However, the use of a similarity matrix S (which associates periods within the fixed contemporary group classification) in the mixed model equations reduced mean square error by as much as 7%. Using simulated observations for the ten herds, highest correlations between true breeding values and estimated breeding values were obtained only for the model using the similarity matrix. ZUSAMMENFASSUNG: Vergleich alternativer Methoden der Behandlung von Wirkungen kontempor?rer Gruppen bei Tiermodellvoraussagen Methoden zur Verbindung zwischen Tieren verschiedener Perioden (Leistungsabschlüsse in 60-Tage-Intervallen einer Abkalbesaison für 400 Tagegewichte ab dem ersten geborenen Kalb) innerhalb kontempor?rer Gruppenklassifikation und Geschlechts-Managementgruppen bei Tiermodellen wurden verglichen. Die Daten stammten von 10 Angusherden. Zuordnung von Tieren an mehr als eine Periode als zuf?llig oder Einbeziehung von Tagen von Beginn der Abkalbeperiode als Kovariable (linear und quadratisch) half wenig zur Verbesserung des Herdenfehlermittelquadrates im Vergleich zu dem Grundmodell, wo keine Verbindungen zwischen Perioden unterstellt wurden. Die Verminderung des Standardfehlers der Voraussage war signifikant (p < als 0,05) nur wenn Perioden innerhalb Geschlechts-Managementgruppen als zuf?llig betrachtet worden sind. Allerdings hat die Verwendung der ?hnlichkeitsmatrix S (welche Perioden innerhalb einer fixen kontempor?ren Gruppenklassifikation assoziiert) in der gemischten Modellgleichungen den Mittelquadratfehler um bis zu 7% reduziert. Unter Verwendung simulierter Beobachtungen für 10 Herden haben sich die h?chsten Korrelationen zwischen wahren Zuchtwerten und gesch?tzten nur bei dem Modell ergeben, das die ?hnlichkeitsmatrix verwendet hat.     

Breed differences and intra-breed genetic variability of dermatoglyphic pattern of cattle

SUMMARY: Muzzle dermatoglyphics - n. ridges, granula and vibrissae - were analysed in various breeds. Differences among these in most traits were significant. Herd effects accounted for about 1/10 of the variance and heritability, estimated by combining sib, halfsib and dam-daughter correlations corrected for herd differences was above 50% for ridges and vibrissae and about 30% for granula. Genetic correlations between ridge counts and n. vibrissae in different nose fields, respectively, were high as they were between the former and n. granula but they were negative or very low between vibrissae and the other two traits. Asymmetry among the counts in the two muzzle sides was significant for nearly all traits, Heritabilities were low, around 10 to 20%, and the crossbreds had less asymmetry than their parental breeds. The correlations among asymmetry measures were low. ZUSAMMENFASSUNG: Rassenunterschiede und genetische Variabilit?t von Flotzmaulmustern Flotzmaulmerkmale - Zahl von Leisten, Warzen und Haaren - wurden in verschiedenen Rassen untersucht. Unterschiede zwischen diesen waren für alle Merkmale signifikant. Herdeneinflüsse verursachten etwa 1/10 der Varianz und Heritabilit?tswerte, gesch?tzt aus Korrelationen zwischen Zwillingen, Halbgeschwistern und T?chter-Müttern, korrigien für Herdeneinflüsse, variierten zwischen 36 und mehr als 50%. Genetische Korrelationen zwischen Leistenzahl und Zahl von Haaren in verschiedenen Flotzmaulfeldern waren hoch, ebenso wie die zwischen ersteren und Zahl von Warzen, aber sie waren negativ oder sehr gering zwischen Haaren und den andern beiden Merkmalen. Asymmetrie zwischen Zahlen in beiden Flotzmaulh?lften war signifikant für fast alle Merkmale. Heritabilit?tswerte waren niedrig, etwa 10-20% und Kreuzungstiere zeigten weniger Asymmetrie als ihre Herkunftsrassen. Die Korrelationen zwischen Asymmetriema?en waren niedrig.     

The effect of dose and concentration on D-xylose absorption in healthy,immature dogs

Nine combinations of dosages and concentrations of D-xylose were given orally to eight clinically normal, immature dogs. The concentrations and dosages of D-xylose consisted of 5%, 10%, and 20% at 250 mg/kg, 500 mg/kg, and 750 mg/kg. Serum samples were collected at 0, 30, 60, 90, 120, and 180 minutes. Serum xylose was quantitated using the phloroglucinol microassay technique. A peak in serum xylose concentration was seen for each treatment combination at 60 or 90 minutes after dosing. The dosage effect was important in influencing serum xylose values (P < 0.0001). As the test solution dosages increased from 250 mg/kg to 500 mg/kg and 750 mg/kg, serum xylose values (when dosage was analyzed over the length of the entire test) rose linearly (R(2) = 0.98). The treatment combinations of 5% and 20% xylose solutions dosed at 750 mg/kg produced the highest serum xylose values at the 60- and 90-minute peak intervals. The independent effect of concentration was significant (p < 0.001) but was overridden by the stronger dosage effect. Serum xylose concentrations varied little statistically (p > 0.05) when the 5%, 10%, and 20% solutions were compared at a specific dosage.