Genetic parameters for total lactation yields of milk,fat, protein,and somatic cell score in New Zealand dairy goats

The aim of this study was to estimate genetic parameters for lactation yields of milk (MY), fat (FY), protein (PY), and somatic cell score (SCS) of New Zealand dairy goats. The analysis used 64,604 lactation records from 23,583 does, kidding between 2004 and 2017, distributed in 21 flocks and representing 915 bucks. Estimates of genetic and residual (co) variances, heritabilities, and repeatabilities were obtained using a multiple‐trait repeatability animal model. The model included the fixed effects of contemporary group (does kidding in the same flock and year), age of the doe (in years), and as covariates, kidding day, proportion of Alpine, Nubian, Toggenburg, and “unknown” breeds (Saanen was used as the base breed), and heterosis. Random effects included additive animal genetic and doe permanent environmental effects. Estimates of heritabilities were 0.25 for MY, 0.24 for FY, 0.24 for PY, and 0.21 for SCS. The phenotypic correlations between MY, FY, and PY ranged from 0.90 to 0.96, and the genetic correlations ranged from 0.81 to 0.93. These results indicate lactation yield traits exhibit useful heritable variation and that multiple trait selection for these traits could improve milk revenue produced from successive generations of New Zealand dairy goats.     

Evaluation of Weaning Strategies for Intensively Reared Australian Freshwater Fish, Murray Cod, Maccullochella peelii peelii

The Australian Murray cod supports a growing national industry. However, with regard to the process of weaning fry, there is a lack of information and optimal procedures need to be developed. The aim of the present investigation was to test the biological and economic efficacy of different weaning strategies for Murray cod. Three weaning strategies were tested on triplicate groups of fish: (1) only Artemia for 5 d, 7 d on Artemia plus starter diet, and 14 d on dry diet only; (2) 12 d on Artemia plus starter diet and 14 d on dry diet only; and (3) directly to dry diet for the entire experimental period. No significant differences were recorded in the growth and feed efficiency, while significantly higher mortality (38.4 ± 0.35%) was recorded in fish weaned directly onto dry diet. Fish subjected to the first 5 d on Artemia only showed a growth reduction during this period, which was compensated by a phase of enhanced growth during the dry‐diet phase. No significant differences were noted in the proximate composition of fish under the different treatments. The economic evaluation suggested that the treatment with the simultaneous supply of Artemia and starter diet is preferable.     

Quantification of the effects of rotation breaks on soil biological properties and their impact on yield decline in sugarcane

Three contrasting rotation breaks (sown pasture, alternate crops and bare fallow) were established at five sites in Queensland, Australia, on land that had been under sugarcane monoculture for at least 20 years. The breaks were in place for 30-42 months at four sites and for 12 months at the fifth site. The effects of the breaks on selected soil biological properties were assessed following the removal of the breaks and before the area was re-planted with sugarcane. At the four sites with the long-term breaks, microbial biomass increased under the pasture break, declined under the bare fallow break and did not change significantly under the crop break, compared to microbial biomass under continual sugarcane. At these sites, populations of the root lesion nematode (Pratylenchus zeae) declined under all three breaks whereas populations of free-living nematodes increased under the pasture and crop breaks but declined under the bare fallow break. At the site with the 12 month breaks, a forage legume pasture increased microbial biomass, reduced lesion nematodes and together with the crop break increased populations of free-living nematodes. At the four sites with the long-term breaks there was an increase in the ratio of fungal:bacterial fatty acids and an increase in fatty acid 16:1ω5c (used as a biomarker for mycorrhizal fungi) under the pasture and crop breaks. Also at these sites, the soil microbial community under the pasture, crop and bare fallow breaks, respectively, showed increased, no change or diminished capacity to utilize carbon substrates compared to the soil microbial community under continual sugarcane. The yield of the sugarcane crop following all three breaks was significantly higher than the yield of the crop following continual sugarcane at each of the sites with the long-term breaks. Examination of the longevity of the effect of the rotation breaks on soil biological properties at the sites with the long-term breaks, suggested that effects on some soil organisms (e.g. lesion nematodes) maybe short-lived.     

Comparative evaluation of molecular diagnostic tests for Nucleospora salmonis and prevalence in migrating juvenile salmonids from the Snake River, USA

Nucleospora salmonis is an intranuclear microsporidian that primarily infects lymphoblast cells and contributes to chronic lymphoblastosis and a leukemia-like condition in a range of salmonid species. The primary goal of this study was to evaluate the prevalence of N. salmonis in out-migrating juvenile hatchery and wild Chinook salmon Oncorhynchus tshawytscha and steelhead O. mykiss from the Snake River in the U.S. Pacific Northwest. To achieve this goal, we first addressed the following concerns about current molecular diagnostic tests for N. salmonis: (1) nonspecific amplification patterns by the published nested polymerase chain reaction (nPCR) test, (2) incomplete validation of the published quantitative PCR (qPCR) test, and (3) whether N. salmonis can be detected reliably from nonlethal samples. Here, we present an optimized nPCR protocol that eliminates nonspecific amplification. During validation of the published qPCR test, our laboratory developed a second qPCR test that targeted a different gene sequence and used different probe chemistry for comparison purposes. We simultaneously evaluated the two different qPCR tests for N. salmonis and foundthat both assays were highly specific, sensitive, and repeatable. The nPCR and qPCR tests had good overall concordance when DNA samples derived from both apparently healthy and clinically diseased hatchery rainbow trout were tested. Finally, we demonstrated that gill snips were a suitable tissue for nonlethal detection of N. salmonis DNA in juvenile salmonids. Monitoring of juvenile salmonid fish in the Snake River over a 3-year period revealed low prevalence of N. salmonis in hatchery and wild Chinook salmon and wild steelhead but significantly higher prevalence in hatchery-derived steelhead. Routine monitoring of N. salmonis is not performed for all hatchery steelhead populations. At present, the possible contribution of this pathogen to delayed mortality of steelhead has not been determined.     

Growth of broilers fed on diets containing dried poultry manure

Sixty 7‐d‐old male broiler chicks were housed in individual metabolism cages and offered one of six purified diets for 14 d. The diets were formulated to have the same ME contents but had different nitrogenous supplements: diet A, was the basal diet, containing PRG essential amino acid (EAA) mixture equivalent to 15 g N/kg; B, basal+12% glutamic acid (GA); C, basal plus EAA mixture equivalent to EAA content of 20.09% DPM; D, basal + EAA+12% GA; E, basal + 20.09% autoclaved DPM; F, basal + 20.09% unautoclaved DPM. The rank order of final body weights at 21 d of chicks fed on these diets were D(292 g) > B(258 g), (F254 g), E(253 g) > C(206 g) > A(180 g), (P<0.05). Chicks fed on diet C had better food conversion efficiencies (FCE) than those fed on diet A (0.449 and 0.374 respectively) and D was better than B (0.592 and 0.533 respectively).

In a second experiment, carried out under field trial conditions using commercial‐type diets formulated to contain DPM, 24 groups, each of about 40 male or female broiler chicks, were given diets containing 0% (P) or 5% (Q) DPM from 1 d of age for 4 weeks. From 4 to 8 weeks one of three diets with 0% (R), 5% (S) or 10% (T) DPM was fed according to a 2 (sexes) x 2 x 3 factorial design. Between o and 4 weeks feeding DPM had no significant effect on body weight or food consumption, but birds fed diet Q had an improved FCE (P<0.05). Between 4 and 8 weeks birds fed on S and T were heavier than the controls at 6 weeks, but this increase was not significant at 8 weeks (P> 0.05). Food consumption was not affected, but the FCE improved with increasing inclusion of DPM. At 8 weeks of age birds fed on Q, were heavier than birds fed on diet P.     

Growth of broilers given diets containing field beans (vicia faba l.) during period the 0 to 4 week

In the first experiment 32 groups, each of about 30 male or female Ross 1 chicks, were given mash diets containing 0, 15, 30 or 45 per cent field beans from one day of age for 4 weeks. From 4 to 8 weeks they were given pelleted diets containing 30 or 45 per cent field beans, the treatments being imposed in a 2 (sexes) x 4x2 factorial design. Increasing the proportion of beans in the diet gave a significant worsening in food conversion ratio and in live‐weight gain to 4 and 8 weeks.

In the second experiment 30 groups, each of about 32 male Ross 1 chicks, were given diets containing o, 30, 45, 30 or 45 per cent beans from one day of age to 4 weeks. In the second and third diets the digestibility of bean protein was assumed to be 100 per cent; in the fourth and fifth diets the digestibility was assumed to be 80 per cent and higher concentrations of other protein supplements were therefore included. All diets were prepared as mash, pellets and ground pellets. From 4 to 8 weeks all groups were given a standard diet, the experiment having a 5 x 3 factorial design. Birds fed the control diet ate significantly less, had a significantly poorer food conversion ratio and weighed significantly less than birds fed the diets containing beans. Growth was similar on all diets containing beans, but food conversion ratio was significantly worsened when the concentration of beans in the diet was increased to 45 per cent. Birds grew best on pellets and grew worst on ground pellets.     

The effects on egg production and egg composition of adding supplements of amino acids and/or urea or dried auto‐claved poultry manure to a low‐protein layer diet

Thirty‐five laying hens of a medium‐weight hybrid strain, aged 10 months, were given a basal diet containing 11.5% protein or the same diet supplemented with 1.54% essential amino acids and/or with two sources of nitrogen for the synthesis of non‐essential amino acids (1.15% urea or 9.7% dried autoclaved poultry manure) for an 8‐week period.

Egg production, food intake, food conversion efficiency, the gross efficiency of nitrogen conversion and the ability of hens to maintain body weight were improved by supplementation with essential amino acids (P < 0.05 or P < 0.01). Supplementation with dried autoclaved poultry manure raised food intake, total egg mass and mean egg weight (P < 0.05), but supplementation with urea alone did not result in significantly higher egg production, perhaps because it failed to increase food intake. Supplementation with essential amino acids and urea to give the equivalent of 16% protein did not result in significantly higher egg production than that obtained with urea alone. The smallest eggs were produced by hens fed on the diet supplemented with urea, and the largest by those fed on the diet supplemented with dried manure (P < 0.001).

The gross composition of eggs was not influenced significantly by dietary treatment but albumen quality was significantly lower on the basal diet and higher on the supplemented diets (P < 0.001). It was highest in eggs from hens fed on the diet supplemented with urea alone.