1. In commercial layer breeding, extensive gene pools are tested and selected for market requirements which must be anticipated at least 5 years ahead. Field results confirm a continuous positive genetic trend in egg output and better feed efficiency which can be converted into land savings.
2. Animal welfare and cage-free housing dominate future needs of the market. Nesting behaviour and minimal tendency to develop feather-pecking or cannibalism without beak treatment are key trait complexes. Stronger shells for longer production cycles without moulting have to be combined with better bones.
3. No single big gene effect can be expected to control the multifactorial problem of feather-pecking. Adjusting the shape of the beak, with a heritability of .10–.25, can contribute to reducing the risk of severe cannibalism.
4. For better skeletal integrity, the assessment of bone quality in pedigree birds housed in enriched cages is done by keel bone palpation or ultrasound measurement of the humerus. Both traits show similar heritabilities in the range of .15–.30 and can be included in a balanced selection approach for performance, quality and welfare traits.
5. The combination of performance testing and genome-wide DNA marker analysis is a promising tool to generate more progress for a balanced performance and behaviour profile. 相似文献
Repeat patient testing‐based quality control (RPT‐QC) is a potential method for veterinary laboratories (eg, that have a limited budget for quality commercial control material [QCM] or that wish to use material with a species‐specific matrix).
Objectives
To determine whether total error (TEa), probability of error detection (Ped), and probability of false rejection (Pfr) similar to that achievable with QC materials can be controlled using RPT‐QC
Methods
Control limits (WBC, RBC, HGB, HCT, MCV, and PLT) for the Advia 120 (n = 23) and scil Vet ABC (n = 22) were calculated using data from normal canine specimens from a routine caseload. Specimens were measured at accession and again after 24 hours. Control limits were validated using 23 additional canine specimens tested similarly. Achievable TEa, Ped, and Pfr were investigated using the Westgard EZRules3 and compared to those achievable with commercial QCM.
Results
Theoretical performance of RPT‐QC and commercial QCM‐QC are similar for 1‐3s with both n = 1 and 1‐3s with n = 2 for all measurands and both instruments. Achievable TEa values for RPT‐QC were close to ASVCP recommendations for most measurands; exceptions were PLT (both instruments) and WBC (scil Vet ABC).
Conclusions
Repeat patient testing‐based quality control advantages include a species‐specific matrix, low‐cost, and absence of QC material deterioration over time (since a fresh specimen is used each day). A potential disadvantage is daily access to normal canine specimens. A challenge is determining control limits, which has a subjective element. Further study is needed to confirm actual RPT‐QC performance and to determine if RPT‐QC with abnormal patient specimens is feasible. 相似文献
The objective of this study was to evaluate the effects of continuous low dose infusion of lipopolysaccharide (LPS) on inflammatory responses and milk production and quality in lactating dairy cows. Eight Holstein cows were assigned to two treatments in a cross‐over experimental design. Cows were infused intravenously either with saline solution or with saline solution containing LPS from Escherichia coli O111:B4 at a dose of 0.01 μg LPS/kg body weight for approximately 6 hr each day during a seven‐day trial. The clinical symptoms and milk production performance were observed. Milk samples were analysed for conventional components, fatty acids and amino acids. And jugular vein and mammary vein plasma samples were analysed for concentrations of cytokines and acute phase proteins. LPS infusion decreased feed intake and milk yield. An increase in body temperature was observed after LPS infusion. LPS infusion also increased plasma concentrations of interleukin‐1β, serum amyloid A, LPS‐binding protein, C‐reactive protein and haptoglobin. LPS infusion decreased the contents of some fatty acids, such as C17:1, C18:0, C18:1n9 (trans) and C18:2n6 (trans), and most amino acids except for methionine, threonine, histidine, cysteine, tyrosine and proline in the milk. The results indicated that a continued low dose infusion of LPS can induce an inflammatory response, decrease milk production and reduce milk quality. 相似文献
The objective of this study was to evaluate the effects of dietary supplementation with zinc oxide nanoparticles (ZnO‐NPs) on the performance, egg quality, Zn retention, immunity responses, superoxide dismutase activity (SOD), egg malondialdehyde (MDA) content, and serum parameters in laying hens in the late phase of production. A total of 288 laying hens at 64 weeks of age were randomly assigned to 4 treatments with 6 replicates, and 12 birds within each group. Experimental diets included a corn‐soybean meal‐based diet (without Zn supplementation) and a basal diet supplemented with 80 mg/kg of Zn‐oxide, ZnO‐NPs, and Zn‐methionine. The results indicated that egg production and egg mass were significantly higher in the Zn‐methionine and ZnO‐NPs groups (p < .05). Also, eggshell thickness and shell strength increased in the ZnO‐NPs group as compared with the other groups (p < .05). Moreover, Zn supplementation decreased egg loss (p < .05). There were significant differences among treatments in Zn deposition in tibiotarsus, liver, pancreas, eggs, and excreta (p < .01). Antibody titre, heterophil (%(, and phytohemagglutinin (PHA) were significantly higher in birds fed with Zn‐supplemented diets (p < .05). In treatments supplemented with ZnO‐NPs and Zn‐methionine, the SOD activity in the liver, pancreas, and plasma was greater as compared with the other treatments (p < .05). The MDA content in eggs was significantly reduced in groups supplemented with Zn (p < .01). Moreover, dietary Zn supplementation significantly affected serum total protein, albumin, glucose, alkaline phosphatase activity, carbonic anhydrase activity, and Zn level (p < .05). In conclusion, this study demonstrated that dietary supplementation with ZnO‐NPs can improve the performance of laying hens. Therefore, ZnO‐NPs can enhance zinc absorption in the intestine of aged layers and can be a more suitable source of zinc than regular Zn‐oxide in diets. 相似文献
The effect of water restriction on body weight, body condition score, milk yield, and milk composition and rheological characteristics in intensively reared Lacaune ewes was evaluated. After 7 days of adaptation, the trial lasted 28 days. Thirty lactating ewes (48 ± 5 months of age; mean value ± standard deviation) at the beginning of third lactation month were divided into three groups (n = 10), corresponding to the following water restriction treatment: a group control received no drinking water restriction (W100), and two groups received water to the extent of 80% and 60% of W100 daily consumption (W80 and W60 group respectively). The effects of water restriction were assessed at the beginning of experiment (D0), at D14 and D28. The W60 group resulted in a significant decrease in body weight, body condition score, milk yield and feed consumption of hay due to the experimental treatment; whereas a marked increase in both W60 and W80 groups of milk lactose, urea, sodium, sodium chloride content and titratable acidity was observed. Rheological parameters of milk, rennet coagulation time and curd‐firming time were positively affected by water restriction treatments, with a decrease in both experimental groups of the time required for the formation of a stable and firm curd. Results highlight the importance of water consumption in dairy sheep. The scarce availability of water, significantly affecting ewes milk production, is worthy of particular attention in arid area where water stress‐resistant breeds should be considered. This study underlines that milk yield, being closely linked to the availability of water of the breeding habitat due to its high water content (about 81%), could be reached in area where water is not a limiting factor without reducing the genetic expression of the animals. Less severe water restrictions, such as 20% of daily voluntary water intake, produce no detrimental effect on milk yield. 相似文献
Meat quality means the characteristics such as appearance is related to palatability in fresh meat or manufactured meat, it includes meat color, meat structure, hardness, marbling, water holding capacity and so on.The physical characteristics of mutton quality determines the consumer acceptability of meat and there is a close relationship between chemical composition of mutton quality and nutrient substance.With the improvement of living standards, consumers are increasingly high demand for mutton.From quantitative to qualitative change, we need to continuously improve mutton quality.At present, the production of high quality animal products has become a hot topic.This paper is a summary of the effects of breed, gender, age, environment and feed nutrition on mutton quality, and aims to provide a scientific basis for improving of mutton quality with nutritional regulation measures. 相似文献