杜洛克猪遗传性跛行的体尺比较

试验采用96头杜洛克猪,这些猪是用反相选择跛行的方法所建立的两个品系的第7代后裔,测定其前肢的尺骨长,尺宽,足长和体长是否有差异。品系分为跛行组和健康组,后者表示在前肢结构上发育良好。所有猪都在二个特定日龄测定,平均117日龄和159日龄,并在每圈猪平均体重达到95kg时进行第三次测量,结束试验。资料用变量分析,混合方程包括品系、重复批次、饲料和性别的影响,并以体重或日龄作协方差分析。健康组猪比跛行组猪足长较长(P<0.01),在117日龄大7％,159日龄大14％,在试验结束时大30％。健康组猪的足宽则几乎和跛行组相等。对不同程度跛行选择的影响也表现在猪的体形方面,健康组猪比跛行组猪在159日龄时体长和尺骨长相对较短,在达到上市体重时体长轻短。对不同程度跛行的选择已使社洛克猪的结构发生了许多变化。     

Morphological modifications among oribatid mites (Acari: Oribatida) in relation to habitat differentiation in mangrove forests

We examined morphological modifications among oribatid species in five microhabitats in mangrove forests in the Ryukyu Islands of Japan. A total of 89 oribatid species were recorded from canopy (leaves and branches), bark of flooded trunks (trunks of 0–50 cm high and knee roots), bark of other trunks higher than 50 cm, and littoral algae in mangrove forests, and the forest-floor soil in an adjacent bank forest. There were no significant differences in the body length, body width, and notogastral length among oribatid species from the five microhabitats. The mean sensillus length of the oribatid species from the forest-floor soil was about twice as long as that from the other microhabitats. Claw morphology was characterized by two attributes: number (monodactyly and tridactyly) and length. In the canopy and trunks, the proportion of tridactyl species was higher than that of monodactyl species. On the other hand, the proportion of tridactyl species in the forest-floor soil accounted for only about 20%, and that in the flooded trunks and littoral algae approximated to zero. The mean claw length was larger in the oribatid species from the flooded trunks and littoral algae than in both monodactyl and tridactyl species from every other microhabitat. Trydactyl species with short claws in the arboreal environments might have been selected by a compromise between grip and mobility for unpredictable environmental changes such as wind and rain. The dominance of monodactyl species with a longer claw in the littoral environments implies a consequence of selection for regular tidal flooding, which requires oribatids to grip tighter on the substrate. The modifications in claw morphology of oribatid mites in mangrove forest might be interpreted as adaptations to a difference in the predictability of the environmental conditions of microhabitats.     

Risk factors influencing lameness and claw disorders in dairy cows

Claw health of dairy cows was investigated in an observational study in different housing systems in Switzerland. Twenty-five professional hoof trimmers examined lameness and claw disorders in 4621 cows on 290 farms during routine hoof trimming. 82 farms had tie-stall barns without exercise (T1) and 166 had tie-stall barns with exercise (T2), another 42 farms kept their animals in loose housing systems with exercise (L2). The prevalence was 10.0% for lameness (LN), 15.7% for sole disorders (SD), 6.1% for white line disorders (WD), 13.6% for heel erosions (HE), and 5.3% for disorders of skin and interdigital space (ID). LN and SD showed the highest prevalence (13.2%; 16.4%) and the highest odds ratio (OR=1.89; 1.33) in T1. WD was more often detected in L2, accounting for 9.4% (OR=1.0). HE was identified most in T2 (17.1%, OR=4.72) and T1 (13.2%, OR=4.45). Disorders of skin and interdigital space were most frequently found in T2 (7.5%, OR=1.55).     

Genetic parameters for claw health and feet and leg conformation traits in Finnish Ayrshire cows

Genetic parameters for different claw disorders, overall claw health and feet and leg conformation traits were estimated for Finnish Ayrshire cows. The merged data set with records of claw health and feet and leg conformation traits consisted of 105 000 observations from 52 598 Finnish Ayrshire cows between 2000 and 2010. The binary claw health data and the linearly scored conformation data were analysed using an animal model and restricted maximum likelihood method by applying the statistical package ASReml. Binomial logistic models with mixed effects were used to estimate genetic parameters for sole haemorrhages, chronic laminitis, white‐line separation, sole ulcer, interdigital dermatitis, heel horn erosion, digital dermatitis, corkscrew claw and overall claw health. Estimated heritabilities for different claw disorders using a binomial logistic model ranged from 0.01 to 0.20. Estimated heritability for overall claw health using a binomial logistic model was 0.08. Estimated heritabilities for feet and leg conformation traits ranged from 0.07 to 0.39. The genetic correlations between claw health and feet and leg conformation traits ranged from ?0.40 to 0.42. All phenotypic correlations were close to zero. The moderate genetic correlation, together with higher heritability of feet and leg conformation traits, showed that RLSV (rear leg side view) is a useful indicator trait to be used together with claw trimming information to increase the accuracy of breeding values for claw health in genetic evaluation.     

Associations between sole ulcer, white line disease and digital dermatitis and the milk yield of 1824 dairy cows on 30 dairy cow farms in England and Wales from February 2003-November 2004

The milk yields of 1824 cows were used to investigate the effect of lesion-specific causes of lameness, based on farmer treatment and diagnosis of lame cows, on milk yield. A three-level hierarchical model of repeated test day yields within cows within herds was used to investigate the impact of lesion-specific causes of lameness (sole ulcer, white line disease, digital dermatitis and other causes) on milk yield before and after treatment compared with unaffected cows. Cattle which developed sole ulcer (SU) and white line disease (WLD) were higher yielding cattle before they were diagnosed. Their milk production fell to below that of the mean of unaffected cows before diagnosis and remained low after diagnosis. In cattle which developed digital dermatitis (DD) there was no significant difference in milk yield before treatment and a slightly raised milk yield immediately after treatment. The estimated milk loss attributable to SU and WLD was approximately 570 and 370 kg, respectively. These results highlight that specific types of lameness vary by herds and within herds they are associated with higher yielding cattle. Consequently lesion-specific lameness reduction programmes targeting the cow and farm specific causes of lameness might be more effective than generic recommendations. They also highlight the importance of milk loss when estimating the economic impact of SU and WLD on the farms profitability.     

Genetic background of claw disorders in the course of lactation and their relationships with type traits

Random regression threshold animal models were applied to binary longitudinal claw disorder data for studying genetic parameters of all claw disorders (ACD), as well as to claw disorders divided into different categories: non‐purulent claw disorders (NPCD), purulent claw disorders (PCD), dermatitis digitalis (DD), sole ulcer (SU), phlegmona (PH), laminitis (LAM) and interdigital hyperplasia (IH) in the course of lactation. Claw disorder data were obtained from 26 651 Holstein cows kept in 15 large‐scale contract herds in the region of Thuringia over a period of 5 years from 2007 to 2012. If a cow had one or more entries of the same disorder, for example, sole ulcer, within an interval of 30 days, she was scored with a ‘1’, and otherwise, she received a score of ‘0’ for healthy. Heritabilities for the same disorder were relatively stable between DIM 50 and DIM 300, but they tended to increase in early and late lactation. Highest heritabilities in the range from 0.20 to 0.34 were estimated for IH, and lowest heritabilities were realized for LAM (~ 0.05). Genetic correlations for same traits between different DIMs were high for adjacent test days, but close to zero for distant test days. The relationship between the sire EBVs for claw disorders and official sire EBVs for the type traits ‘foot angle’ was slightly antagonistic with correlation coefficients in the range from 0.05 (DD) to 0.33 (PH). Correlations between lactation EBVs for hock quality, rear leg rear view and the feet and leg index with EBVs for claw disorders were slightly favourable and ranged between ?0.01 (rear leg rear view correlated with SU) and ?0.43 (hock quality correlated with PH). Regarding daily EBVs for claw disorders, the strongest correlation coefficient was of value ?0.46 (LAM early in lactation correlated with the feet and leg index). Genetic parameters from the random regression model were verified by applying a single‐trait repeatability model. Correlation coefficients between lactation EBVs from the random regression model and lactation EBVs from the repeatability model for the same claw disorder were close to 1. Correlations were lower between EBVs from single test days and lactation EBVs from the repeatability models, with a minimal value of 0.58 for PCD measured at day 20.     

Prevalence of claw lesions in Norwegian dairy cattle housed in tie stalls and free stalls

Approximately 88% of Norwegian dairy cattle are housed in tie stalls. Free-stall housing will be implemented for all cattle within 20 years. This means that most existing barns have to be rebuilt in the near future. We designed our study to estimate the prevalence of claw lesions in Norway and to reveal possible differences between tie stalls and free stalls. Fifty-five tie-stall herds and 57 free-stall herds were sampled by computerized systematic selection and 2665 cows were trimmed by 13 claw trimmers, during the late winter and spring of 2002. The claw trimmers had been taught diagnosing and recording of claw lesions. Environmental factors, management and feeding routines also were recorded. Forty-eight percent of cows housed in tie stalls had one or more claw lesions versus 71.8% in free stalls. Prevalences recorded in the hind claws were: 4.2% of the animals had dermatitis in tie stalls versus 5.7% in free stalls; 7.9% versus 38.0% had heel–horn erosions; 7.3% versus 13.6% had haemorrhages of the white line; 11.7% versus 20.4% had haemorrhages of the sole; 2.8% versus 3.2% had sole ulcers and 5.5% versus 9.7% had white-line fissures. Most lesions were mild. A model was designed to estimate cluster effects within herd and within claw trimmer. The cluster effect within herd was significant for all lesions. The cluster effect within claw trimmer was only significant for heel–horn erosions in front and hind claws and for white-line fissures in front claws. Agreements between some of the claw lesions were revealed. The study confirms that in Norwegian dairy cattle, most claw lesions are more prevalent in free stalls than in tie stalls.     

Bovine claw and limb disorders related to culling and carcass characteristics

As part of a cross-sectional study in Norwegian Red Cattle, associations of lameness, lesions at the tarsus, claw shapes and claw lesions to time of culling and carcass characteristics were examined. Fifty-five tie-stall herds and 57 free-stall herds were sampled by computerized systematic selection and 2665 cows were trimmed by 13 specifically trained claw trimmers, during the late winter and spring of 2002. After exclusions, 2645 cows were included in this study. Most claw lesions were mild (score 1). The prevalence of moderate and severe lesions (2 + 3) did not exceed 5% for any of the lesions. The hazard ratios (HR) for time of culling were identified using Cox regression analyses incorporating herd as a random effect in a positive stable frailty model. Associations to carcass characteristics were examined using regression analysis (Proc Mixed) with lameness and each disorder as independent fixed variables. Lameness in lactation 1 was associated with earlier culling (HR = 4.2) and lower conformation class of the carcass (− 0.76) whereas lameness in lactation 2 was associated with lower carcass weight (− 42.5 kg) and economic value (− 2113 Norwegian kroner, 8.1 NOK = 1 €). Lameness in lactations ≥ 3 was associated with lower conformation class (− 0.57). Lesions at the tarsus in lactations ≥ 3 were associated with lower carcass weight (− 15.9 kg), conformation class (− 0.51), fat cover class (− 1.2) and economic value (− 650 NOK). Corkscrewed claws in lactation 2 were associated with lower weight (− 21.6 kg). Heel-horn erosions score 1–2–3 in lactation 1 were associated with lower fat cover class (− 0.68), and heel-horn erosions score 3 in lactations ≥ 2 were associated with earlier culling (HR = 7.7). Haemorrhages of the white line score 1–2–3 in lactation 2 were associated with higher economic value (506 NOK). Haemorrhages of the sole score 2–3 in lactation ≥ 2 were associated with earlier culling (HR = 2.1). Sole ulcers score 1–2–3 in lactation 2 were associated with higher conformation class (0.95).     

Effects of outdoor winter housing and feeding level on performance and blood metabolites of suckler cows fed whole-crop barley silage

The experiment studied the effects of long-term cold climatic housing conditions at a latitude of 62°N on pregnant Hereford cows and their progeny. Thirty-five cows in their third parity were overwintered in outdoor facilities with either a rain-shelter or a three-wall shelter, or in an uninsulated barn. Whole-crop barley silage was offered to the cows either ad libitum or restricted supplemented with oats. The dry matter intake on the restricted diet was 75% of that on the ad libitum diet. The cow live weight (LW) averaged 670 kg at the onset of the experiment. During winter the cows outdoors on the restricted diet maintained their LW while those on the ad libitum diet gained LW (P < 0.05, − 3 vs. 41 kg). On pasture, the LW gain (LWG) was 61 and 32 kg (P < 0.05) for the cows overwintered outdoors on the restricted and on the ad libitum diets, respectively. The initial body condition score (BCS, Scale: 0–5) of the cows averaged 2.90. During winter the cows outdoors on the restricted diet decreased and those on the ad libitum diet increased the BCS (P < 0.01, − 0.14 vs. 0.21). On pasture, the cows overwintered outdoors on the restricted diet increased the BCS more than those overwintered on the ad libitum diet (P < 0.05, 0.31 vs. 0.08). No signs of extraordinary stress, massive consumption of energy stores, frequent muscle injuries or severe inflammations occurred in any of the groups according to blood analyses of cows, e.g. cortisol, long-chain fatty acids, aspartate aminotransferase, creatine kinase and white blood cell count. The calving period was from 11 March to 21 April. Only one indoor calving was classified as difficult due to faulty disposition leading to the loss of the calf. All outdoor calvings were easy. The LWG of the indoor calves of cows on the ad libitum diet was poorer (P < 0.05) pre the grazing period than that of the outdoor calves of cows on the ad libitum diet. On pasture and during the entire experiment the LWG was similar for all calves, averaging 1335 and 1251 g/d, respectively. The breeding season was 82 days. Thirty cows out of 33 were observed to be pregnant after the mating period. All the facilities offered adequate shelter for the mature, pregnant suckler cows. The restricted offering of whole-crop barley silage provided, on average, 101 MJ metabolizable energy/d and gave enough energy for the cows.