A case in variant in cow's milk is atherogenic

Casein is a major protein in cow's milk that occurs in several variant forms, two of which are beta-casein A(1) and beta-casein A(2). The levels of these two proteins vary considerably in milk dependent on the breed of cow, and epidemiology studies suggest that there is a relationship between their consumption and the degree of atherosclerosis. In the present study, the direct effect of consumption of beta-casein A(1) vs beta-casein A(2) on atherosclerosis development was examined in a rabbit model. Sixty rabbits had their right carotid artery balloon de-endothelialised at t = 0, divided randomly into 10 groups (n = 6 per group), then for 6 weeks fed a diet containing 0, 5, 10 or 20% casein isolate, either beta-casein variant A(1) or A(2) made up to 20% milk protein with whey. Some groups had their diets supplemented with 0.5% cholesterol. Blood samples were collected at t = 0, 3 and 6 weeks and rabbits were sacrificed at t = 6 weeks. In the absence of dietary cholesterol, beta-casein A(1) produced significantly higher (P < 0.05) serum cholesterol, LDL, HDL and triglyceride levels than whey diet alone, which in turn produced higher levels than beta-casein A(2). Rabbits fed beta-casein A(1) had a higher percent surface area of aorta covered by fatty streaks than those fed beta-casein A(2) (5.2+/-0.81 vs 1.1+/-0.39, P < 0.05) and the thickness of the fatty streak lesions in the aortic arch was significantly higher (0.04+/-0.010 vs 0.00, P < 0.05). Similarly, the intima to media ratio (I:M) of the balloon injured carotid arteries in A(1) fed animals (0.77+/-0.07) was higher than in those that consumed A(2) (0.57+/-0.04) or whey (0.58+/-0.04), but this did not reach significance. In the presence of 0.5% dietary cholesterol, the thickness of the aortic arch lesions was higher (P < 0.05) in 5, 10 and 20% casein A(1) fed animals compared with their A(2) counterparts, while other parameters were not significantly different. It is concluded that beta-casein A(1)is atherogenic compared with beta-casein A(2). (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.

Quantitative description of the interaction between folate and the folate-binding protein from cow's milk

A detailed study has been carried out on the dependence of folate binding on the concentration of FBP (folate-binding protein) at pH 5.0, conditions selected to prevent complications arising from the pre-existing self-association of the acceptor. In contrast with the mandatory requirement that reversible interaction of ligand with a single acceptor site should exhibit a unique, rectangular hyperbolic binding curve, results obtained by ultrafiltration for the FBP-folate system required description in terms of (i) a sigmoidal relationship between concentrations of bound and free folate and (ii) an inverse dependence of affinity on FBP concentration. These findings have been attributed to the difficulties in determining the free ligand concentration in the FBP-folate mixtures for which reaction is essentially stoichiometric. This explanation also accounts for the similar published behaviour of the FBP-folate system at neutral pH, which had been attributed erroneously to acceptor self-association, a phenomenon incompatible with the experimental findings because of its prediction of a greater affinity for folate with increasing FBP concentration.

Survey for papillomatous digital dermatitis in Australian dairy cattle

Objective To determine whether Treponema-associated papillomatous digital dermatitis (PDD) occurs in Australian dairy cattle. Design Mail-out questionnaire and histological and bacteriological examination of biopsy tissue from suspect PDD lesions. Procedure The questionnaire was mailed to 375 veterinarians to evaluate their knowledge of PDD, determine if they had observed the disease in Australian dairy cattle, and to request biopsy material from suspicious cases. Biopsies were examined for histological and bacteriological evidence of PDD, including for the presence of spirochaetes. Results Eighty-eight replies to the questionnaire were received (23.5%). Of 52 respondents who were aware of PDD as a possible cause of lameness, 26 reported observing the condition in Australian cattle. Of 32 respondents who were unaware of the condition, 6 reported observing lesions that might have been PDD. The majority of reports of PDD-like lesions came from the southern Australian states, the condition occurring during periods of high rainfall and proving responsive to topical or parenteral application of antimicrobials. Biopsies from five erosive lesions showed histological similarity to PDD whereas biopsies from five proliferative lesions were consistent with chronic inflammation, fibroma or cutaneous papilloma. The presence of spirochaetes was not demonstrated in any of the lesions by histological or bacteriological methods. Conclusion Anecdotal reports and analysis of biopsy material confirm that a condition similar to PDD does occur sporadically in dairy cattle in southern Australia. However, this condition has so far not been shown to be associated with the presence of spirochaetes in the lesions.

Lameness, metabolic and digestive disorders, and technical efficiency in Danish dairy herds: a stochastic frontier production function approach

The relationship between reported treatments of lameness, metabolic disorders (milk fever, ketosis), digestive disorders, and technical efficiency (TE) was investigated using neutral and non-neutral stochastic frontier analysis (SFA). TE is estimated relative to the stochastic frontier production function for a sample of 574 Danish dairy herds collected in 1997. Contrary to most published results, but in line with the expected negative impact of disorders on the average cow milk production, herds reporting higher frequencies of milk fever are less technically efficient. Unexpectedly, however, the opposite results were observed for lameness, ketosis, and digestive disorders. The non-neutral stochastic frontier indicated that the opposite results are due to the relative. high productivities of inputs. The productivity of the cows is also reflected by the direction of impact of herd management variables. Whereas efficient farms replace cows more frequently, enroll heifers in production at an earlier age, and have shorter calving intervals, they also report higher frequency of disorder treatments. The average estimated energy corrected milk loss per cow is 1036, 451 and 242 kg for low, medium and high efficient farms. The study demonstrates the benefit of the stochastic frontier production function involving the estimation of individual technical efficiencies to evaluate farm performance and investigate the source of inefficiency. (C) 2004 Elsevier B.V. All rights reserved.

Relationships of Efficiency to Reproductive Disorders in Danish Milk Production: A Stochastic Frontier Analysis

Relationships of various reproductive disorders and milk production performance of Danish dairy farms were investigated. A stochastic frontier production function was estimated using data collected in 1998 from 514 Danish dairy farms. Measures of farm-level milk production efficiency relative to this production frontier were obtained, and relationships between milk production efficiency and the incidence risk of reproductive disorders were examined. There were moderate positive relationships between milk production efficiency and retained placenta, induction of estrus, uterine infections, ovarian cysts, and induction of birth. Inclusion of reproductive management variables showed that these moderate relationships disappeared, but directions of coefficients for almost all those variables remained the same. Dystocia showed a weak negative correlation with milk production efficiency. Farms that were mainly managed by young farmers had the highest average efficiency scores. The estimated milk losses due to inefficiency averaged 1142, 488, and 256 kg of energy-corrected milk per cow, respectively, for low-, medium-, and high-efficiency herds. It is concluded that the availability of younger cows, which enabled farmers to replace cows with reproductive disorders, contributed to high cow productivity in efficient farms. Thus, a high replacement rate more than compensates for the possible negative effect of reproductive disorders. The use of frontier production and efficiency/ inefficiency functions to analyze herd data may enable dairy advisors to identify inefficient herds and to simulate the effect of alternative management procedures on the individual herd's efficiency.

Monensin supplementation of lactating cows fed tropical grasses and cane molasses or grain

Effects of monensin (Mon) on performance of Holstein-Friesian cows fed tropical grasses and cane molasses (M) or cereal grain were examined in three experiments. In experiment I (incomplete 4 x 4 Latin square), three rumen-fistulated cows [188 I I days in milk (DIM)] were fed mixed diets based on rhodes grass (Chloris gayana cv. Callide) bay where M was substituted for wheat grain (W) at rates of 0 (MO), 125 (M 125) or 250 (M250) g/kg dry matter (DM). A fourth diet contained M250 plus 0.02 g Mon/kg DM (M250 + Mon). Substituting M for W tended (P < 0.10) to decrease the ratio of rumen molar proportions of acetate+butyrate (Bu):propionate (Pr) (4.3 versus 3.8 and 4.0 for M0, M125 and M250, respectively). There were no treatment effects (P> 0.10) on intake, organic matter digestibility, milk production or liveweight (LW) change. In experiment 2, 48 cows (173 &PLUSMN; 28.3 DIM) grazing kikuyu (Pennisetum clandestinum cv. common) pastures and supplemented with maize silage and a grain-based concentrate were offered either M (2.6 kg DM/(cow day)) or barley grain (B) (2.7 kg DM/(cow day)). Within each supplement type, half were fed 0 or 320 mg of Mon/(cow day). There were Mon x supplement interactions (Mon x S; P < 0.05) on the rumen molar proportion of Pr and Bu at 15:00 h, with B + Mon having the highest value for Pr (0.259 mmol/mmol) and lowest value for Bu (0.121 mmol/mmol). A Mon x S effect (P < 0.05) on milk fat content was noted with Mon causing a lower value regardless of energy source (31 and 36 g/l versus 40 and 38 g/l for B + Mon, M + Mon, B - Mon and M - Mon, respectively). As a main effect, M as opposed to B, reduced yields of milk (P < 0.05; 16.21/(cow day) versus 18.01/(cow day)) and protein (P < 0.05; 479 g/(cow day) versus 538 g/(cow day)). Monensin reduced milk fat yield (P < 0.05; 669 g/(cow day) versus 562 g/(cow day)), raised milk protein concentration (P < 0.05; 31 g/l versus 29 g/l) and caused LW gain rather than loss (P < 0.05; +0.06 kg/(cow day) versus -0.30 kg/(cow day)). No treatment effects on pasture intake were noted. In experiment 3, 48 cows (91 &PLUSMN; 16.1 DIM) grazing kikuyu pasture and supplemented with grain-based concentrate, sugar cane silage and 2.7 kg DM(cow day) of M were supplemented with either 0 or 320 mg Mon/(cow day). Monensin reduced (P < 0.05) milk fat content (33 g/l versus 30 g/l) and tended (P < 0.10) to reduce milk protein content (29 g/l versus 28 g/l). No effects of Mon on other milk production parameters, LW change or pasture intake were noted. Feeding monensin to mid-lactation Holstein-Friesian cows offered diets based on tropical grasses, and cane molasses or grain, improves rumen fermentation efficiency, thereby improving energy efficiency resulting in higher LW gain. Monensin had no effect on milk yield, but reduced milk fat concentration.

Concurrent microscopic observations and activity measurements of cellulose hydrolyzing and methanogenic populations during the batch anaerobic digestion of crystalline cellulose

This study compares process data with microscopic observations from an anaerobic digestion of organic particles. As the first part of the study, this article presents detailed observations of microbial biofilm architecture and structure in a 1.25-L batch digester where all particles are of an equal age. Microcrystalline cellulose was used as the sole carbon and energy source. The digestions were inoculated with either leachate from a 220-Lanaerobic municipal solid waste digester or strained rumen contents from a fistulated cow. The hydrolysis rate, when normalized by the amount of cellulose remaining in the reactor, was found to reach a constant value 1 day after inoculation with rumen fluid, and 3 days after inoculating with digester leachate. A constant value of a mass specific hydrolysis rate is argued to represent full colonization of the cellulose surface and first-order kinetics only apply after this point. Additionally, the first-order hydrolysis rate constant, once surfaces were saturated with biofilm, was found to be two times higher with a rumen inoculum, compared to a digester leachate inoculum. Images generated by fluorescence in situ hybridization (FISH) probing and confocal laser scanning microscopy show that the microbial communities involved in the anaerobic biodegradation process exist entirely within the biofilm. For the reactor conditions used in these experiments, the predominant methanogens exist in ball-shaped colonies within the biofilm. (C) 2005 Wiley Periodicals, Inc.

Evolutionary conservation and murine embryonic expression of the gene encoding the SERTA domain-containing protein CDCA4 (HEPP)

Cdca4 (Hepp) was originally identified as a gene expressed specifically in hematopoietic progenitor cells as opposed to hematopoietic stem cells. More recently, it has been shown to stimulate p53 activity and also lead to p53-independent growth inhibition when overexpressed. We independently isolated the murine Cdca4 gene in a genomic expression-based screen for genes involved in mammalian craniofacial development, and show that Cdca4 is expressed in a spatio-temporally restricted pattern during mouse embryogenesis. In addition to expression in the facial primordia including the pharyngeal arches, Cdca4 is expressed in the developing limb buds, brain, spinal cord, dorsal root ganglia, teeth, eye and hair follicles. Along with a small number of proteins from a range of species, the predicted CDCA4 protein contains a novel SERTA motif in addition to cyclin A-binding and PHD bromodomain-binding regions of homology. While the function of the SERTA domain is unknown, proteins containing this domain have previously been linked to cell cycle progression and chromatin remodelling. Using in silico database mining we have extended the number of evolutionarily conserved orthologues of known SERTA domain proteins and identified an uncharacterised member of the SERTA domain family, SERTAD4, with orthologues to date in human, mouse, rat, dog, cow, Tetraodon and chicken. Immunolocalisation of transiently and stably transfected epitope-tagged CDCA4 protein in mammalian cells suggests that it resides predominantly in the nucleus throughout all stages of the cell cycle. (c) 2006 Elsevier B.V. All rights reserved.

Impacts of feeding system and season on milk composition and Cheddar cheese yield in a subtropical environment

Milk obtained from cows on 2 subtropical dairy feeding systems were compared for their suitability for Cheddar cheese manufacture. Cheeses were made in a small-scale cheesemaking plant capable of making 2 blocks ( about 2 kg each) of Cheddar cheese concurrently. Its repeatability was tested over 10 separate cheesemaking days with no significant differences being found between the 2 vats in cheesemaking parameters or cheese characteristics. In the feeding trial, 16 pairs of Holstein - Friesian cows were used in 2 feeding systems (M1, rain-grown tropical grass pastures and oats; and M5, a feedlot, based on maize/barley silage and lucerne hay) over 2 seasons ( spring and autumn corresponding to early and late lactation, respectively). Total dry matter, crude protein (kg/cow. day) and metabolisable energy (MJ/cow.day) intakes were 17, 2.7, and 187 for M1 and 24, 4, 260 for M5, respectively. M5 cows produced higher milk yields and milk with higher protein and casein levels than the M1 cows, but the total solids and fat levels were similar (P > 0.05) for both M1 and M5 cows. The yield and yield efficiency of cheese produced from the 2 feeding systems were also not significantly different. The results suggest that intensive tropical pasture systems can produce milk suitable for Cheddar cheese manufacture when cows are supplemented with a high energy concentrate. Season and stage of lactation had a much greater effect than feeding system on milk and cheesemaking characteristics with autumn ( late lactation) milk having higher protein and fat contents and producing higher cheese yields.

Long-term persistence of multi-drug-resistant Salmonella enterica serovar Newport in two dairy herds

Objective - To evaluate the association between maintaining joint hospital and maternity pens;and persistence of multi-drug-resistant (MDR) Salmonella enterica serovar Newport on 2 dairy farms. Design - Observational study. Sample Population - Feces and environmental samples from 2 dairy herds. Procedure - Herds were monitored for fecal shedding of S enterica Newport after outbreaks of clinical disease. Fecal and environmental samples were collected approximately monthly from pens housing sick cows and calving cows and from pens containing lactating cows. Cattle shedding the organism were tested serially on subsequent visits to determine carrier status. One farm was resampled after initiation of interventional procedures, including separation of hospital and maternity pens. Isolates were characterized via serotyping, determination of antimicrobial resistance phenotype, detection of the CMY-2 gene, and DNA fingerprinting. Results - The prevalence (32.4% and 33.3% on farms A and B, respectively) of isolating Salmonella from samples from joint hospital-maternity pens was significantly higher than the prevalence in samples from pens housing preparturient cows (0.8%, both farms) and postparturient cows on Farm B (8.8%). Multi-drug-resistant Salmonella Newport was isolated in high numbers from bedding material, feed refusals, lagoon slurry, and milk filters. One cow excreted the organism for 190 days. Interventional procedures yielded significant reductions in the prevalences of isolating the organism from fecal and environmental samples. Most isolates were of the C2 serogroup and were resistant to third-generation cephalosporins. Conclusions and Clinical Relevance - Management practices may be effective at reducing the persistence of MDR Salmonella spp in dairy herds, thus mitigating animal and public health risk.

Resolution and characterisation of multiple isoforms of bovine kappa-casein by 2-DE following a reversible cysteine-tagging enrichment strategy

Visualisation of multiple isoforms of kappa-casein on 2-D gels is restricted by the abundant alpha- and beta-caseins that not only limit gel loading but also migrate to similar regions as the more acidic kappa-casein isoforms. To overcome this problem, we took advantage of the absence of cysteine residues in alpha(S1)- and beta-casein by devising an affinity enrichment procedure based on reversible biotinylation of cysteine residues. Affinity capture of cysteine-containing proteins on avidin allowed the removal of the vast majority of alpha(S1)- and beta-casein, and on subsequent 2-D gel analysis 16 gel spots were identified as kappa-casein by PMF. Further analysis of the C-terminal tryptic peptide along with structural predictions based on mobility on the 2-D gel allowed us to assign identities to each spot in terms of genetic variant (A or B), phosphorylation status (1, 2 or 3) and glycosylation status (from 0 to 6). Eight isoforms of the A and B variants with the same PTMs were observed. When the casein fraction of milk from a single cow, homozygous for the B variant of kappa-casein, was used as the starting material, 17 isoforms from 13 gel spots were characterised. Analysis of isoforms of low abundance proved challenging due to the low amount of material that could be extracted from the gels as well as the lability of the PTMs during MS analysis. However, we were able to identify a previously unrecognised site, T-166, that could be phosphorylated or glycosylated. Despite many decades of analysis of milk proteins, the reasons for this high level of heterogeneity are still not clear.