Postpartum production performance of dairy heifers may be enhanced by prepartum milking by alleviating the stress of the periparturient period. The objective of this study was to determine the impact of prepartum milking of dairy heifers on postpartum reproduction, udder health, milk production and other associated production characteristics. Pregnant heifers (Holstein, n=21; Jersey n=10) were assigned to either a prepartum milked (premilked, n=15) or control (n=16) group. Premilked heifers were milked twice daily starting 3 weeks prior to anticipated calving dates, and milk yield recorded at each milking. All heifers were evaluated on days 21, 14 and 7 before calving, and udder oedema scores and milk conductivity readings were recorded. Following calving, measurements were taken twice weekly to assess udder oedema, milk conductivity (indicative of udder infection), and reproductive health, which included palpation for uterine tone and uterine position, vaginal electrical impedance (VEI) and the quantification of cross-sectional area of the uterine horns (uterine difference) by transrectal ultrasonography. Uterine tone, uterine position, uterine difference, and VEI did not differ (P>0·10) with treatment. Overall, up to week six inclusive, postpartum premilked heifers had lower (P<0·01) udder oedema scores than control heifers and up to week five inclusive, had lower (P<0·01) milk conductivity readings (indicative of fewer incidences of udder infections) than control heifers. The premilked heifers of both breeds produced more milk (P<0·01) at calving and more milk overall from calving to day 60 postpartum than the control heifers. In summary, udder health and milk production were improved post calving in premilked heifers compared with controls. However, no overt differences in reproductive characteristics were observed between the premilked and control heifers.

Microbial diversity of the raw milk for the production of Fior di Latte di Agerola and its changes during cheesemaking were studied. Viable counts showed that at the end of curd ripening, loads of lactic acid bacteria, both mesophilic and thermophilic rods and cocci, higher than those commonly evidenced in similar cheeses produced by using natural or commercial starters, were detected. Identification of 272 isolates, supported by molecular diagnostic aids, evidenced representative cultures of a high number of bacterial taxa of interest as participating in the process, although most of the isolates belonged to Lactococcus lactis and Lactobacillus helveticus species. RAPD-PCR and REA-PFGE biotyping were performed for the isolates of the above species and it was shown that most of the strains isolated from the raw milk occurred during the whole cheesemaking process, and an active role of these strains in the fermentation was supposed. The results offer further proof of the importance of the raw milk as source of technologically interesting strains of lactic acid bacteria capable of driving the fermentation of traditional cheeses.

Maintaining dry matter intake (DMI) during the last 2 weeks of gestation is difficult, and a failure to do so is reported to have negative implications on postcalving DMI (Grummer, 1995) and subsequent milk production (Bertics et al. 1992). DMI at the end of gestation, but excluding the last 1–2 d before parturition, can decrease by up to 30% (Lodge et al. 1975; Bertics et al. 1992; Dewhurst et al. 2000). The extent of the decline varies and may be influenced by a number of factors, such as level of feeding precalving (Lodge et al. 1975; Murphy, 1999; Dewhurst et al. 2000) or amount of non-structural carbohydrates in the precalving diet (Coppock et al. 1972; Forbes, 1995). Most studies were undertaken with cows receiving total mixed ration (TMR) or conserved forage and concentrates. However, this may have been one of the reasons for the witnessed depression. Increasing the proportion of rapidly fermentable carbohydrates or alternatively decreasing the fibre concentration in the precalving diet appears to exacerbate this decline (Coppock et al. 1972; Minor et al. 1998). Research suggests that ruminants may actively select against concentrates as plasma oestrogen concentrations increase, such as happens in the weeks preceding parturition (Forbes, 1995). When hay was offered ad libitum, increasing concentrations of oestrogen (up to 400 μg infused intravenously) had no effect. However, when a complete pelleted diet was offered, a 90-μg infusion caused a lower feed intake, followed by a significant increase after treatment was stopped. The lack of depression in precalving DMI reported by Coppock et al. (1972) and Vazquez-Anon et al. (1994) when forage was the principal component of the diet, supports this.

Composite milk somatic cell counts (CMSCC) from four separate datasets, containing 3338, 350, 1408 and 1404 herds, were used. All herds were enrolled in the Norwegian Dairy Herd Recording System (NDHRS). The aim was to investigate associations between CMSCC at calving or prior to drying-off and future CMSCC in the remaining or subsequent lactation. CMSCC was determined using Fossomatic 5000® cell counters (Foss Electric, Hillerød, Denmark) according to IDF recommendations (International Dairy Federation, 1984) and a natural logarithmic transformation of the CMSCC data (lnCMSCC) was performed. Results obtained were arranged according to parity and lactation stage and regression models and general linear mixed models were applied, the latter model to account for clustering between herds. The best associations between CMSCC at calving or prior to drying-off and future CMSCC in the remaining or subsequent lactation were found by using at least two CMSCC test days after calving or prior to drying-off. The geometric mean of the second and third or the first three CMSCC test days explained 50% of the variation in future CMSCC in first parity cows. This information was accessible at 151 days in milk (DIM) in bimonthly tested herds, and at 87 DIM for monthly tested herds. There was not a large difference using two or three single consecutive weighted CMSCC test days compared with the geometric mean of two or three CMSCC test days. Our findings indicate the need of using at least two CMSCC test days and, if only one CMSCC test day is used, it should be obtained after 14 d post-calving or preferably after 30 DIM.

Colostrum and milk samples from twelve Tunisian camels were analysed for concentration of immunoglobulin G (IgG), α-lactalbumin (α-la), serum albumin (CSA) and lactoferrin throughout the first 14 milkings post partum (7 days of lactation) using single radial immunodiffusion assay. Concentrations (mg/ml, means±SD) at first milking were IgG, 100·7±60·4; α-la, 2·2±0·7; CSA, 8·5±3·6 and lactoferrin, 1·2±0·3. Large variations were recorded for IgG and CSA concentrations (11·8–211·1 mg/ml and 2·9–13·8 mg/ml respectively) Concentrations of IgG and CSA dropped abruptly in the subsequent milkings while α-la concentration increased until milking 5 and then decreased slowly. Lactoferrin dropped only from milking 7. Mean IgG concentrations were 3·6 and 2·5 mg/ml at milking 9 and 13 respectively. However, IgG concentration did not differ significantly, at the 1% level, from milkings 11 to 14. The contribution of CSA to the increase in whey proteins in early milks was greater than that described in the bovine and caprine species.

High pressure (HP) treatment affects many constituents of milk (for reviews see Huppertz et al. 2002; Needs, 2002); particular in the properties of casein micelles in HP-treated milk differ considerably from their counterparts in untreated milk. In milk treated at 100–200 MPa, average casein micelle size differs little from that of untreated milk (Needs et al. 2000a; Huppertz et al. 2004a; Regnault et al. 2004; Anema et al. 2005), but micelle size in milk treated at 250 MPa for [ges ]15 min is considerably higher than in untreated milk, probably due to HP-induced aggregation of casein micelles (Huppertz et al. 2004a,b; Regnault et al. 2004); after treatment at 300–800 MPa, micelle size is ~50% lower than that in untreated milk (Needs et al. 2000a; Huppertz et al. 2004a,b; Anema et al. 2005). HP-induced changes in average casein micelle size are irreversible on subsequent storage, except for the increase in micelle size after treatment at 250 MPa (Huppertz et al. 2004a).

Despite more than 30 years of research into mastitis diagnostics, there are few alternatives to the somatic cell count (SCC) in practical use for identification of cows with subclinical mastitis. Mastitis is not only an animal welfare problem, but also affects the yield, composition and technological properties of milk. Hence, dairy cooperatives give farmers a premium quality payment to encourage low SCC although there is no clear scientific data defining the level of SCC in bulk tank milk that is associated with additional benefits in terms of milk quality. Recent research on alternative markers for inflammatory reactions in the lactating cow, e.g. in mastitis, includes investigations of the acute phase protein, haptoglobin (Hp). So far, the content of Hp in milk has mainly been studied in relation to mastitis diagnostics, with little attention given to its importance for milk composition and technological properties. At present, Hp in milk is measured using ELISA, but this technique is not suitable for routine large-scale analysis. In recent years, optical biosensor technology has been used for automated and rapid quantitative analysis of different components in milk, but so far not for analysis of acute phase proteins. The aim of the present study was to develop a rapid and sensitive biosensor method to determine Hp in milk. An affinity sensor assay based on the interaction between Hp and haemoglobin was developed using surface plasmon resonance (SPR) biosensor technology. The assay was used to analyse Hp in composite milk samples from cows without any clinical signs of mastitis and quarter milk samples with a weak to strong reaction in the California Mastitis Test (CMT). A commercial ELISA for determination of Hp in milk was used for comparison. The limit of detection (LOD) of the biosensor assay was determined as 1·1 mg/l. Within-assay and between-day variations were determined both with bulk tank milk spiked with human Hp and with composite milk samples containing bovine Hp. Coefficients of variation varied between 3·6 and 8·6% at concentrations between 4·0 and 12 mg/l, respectively. Agreement between the results obtained by the biosensor assay and the ELISA was satisfactory; however, the results obtained by the biosensor were generally lower than the results obtained by the ELISA. Possible explanations for this observation are discussed.

The capability of goats to maintain milk production during water deprivation is remarkable and not yet fully understood. The aim of the present study was to investigate whether intravenous infusions of hypertonic NaCl cause release of both vasopressin and oxytocin and whether the peptides, in combination with the hyperosmolality, affect milk flow and milk composition. Six Swedish domestic landrace goats in their first to third lactation were milked every 30 min during experiments. Hypertonic NaCl (HNaCl) or isotonic NaCl (IsoNaCl) were infused for 90 min. Goats were not allowed to drink during infusions. Plasma vasopressin concentration increased during HNaCl infusions, and did not change in response to IsoNaCl infusions. Plasma oxytocin concentration did not change during either infusion. Milk flow was maintained during the infusions. Milk fat concentration decreased in the three samples taken before onset of the infusions, but then increased gradually during HNaCl infusions, while it continued to fall during the IsoNaCl infusions. Milk osmolality followed the rise in plasma osmolality during the HNaCl infusions and did not change in IsoNaCl experiments. Milk lactose concentration increased throughout both series of experiments, the concentration being higher during HNaCl infusions. Milk protein concentration did not change during HNaCl infusions, but fell in the IsoNaCl experiments. It is concluded that the hyperosmolality in combination with elevated plasma vasopressin levels did not disturb the secretory activity of the mammary cells, but rather facilitated emptying of the alveolar milk. Such a mechanism may help to explain the sustained milk production in water deprived goats.

The influence of ethanol on the rennet-induced coagulation of milk was studied to investigate potential synergistic effects of these two mechanisms of destabilisation on the casein micelles. Addition of 5% (v/v) ethanol reduced the rennet coagulation time (RCT) of milk, whereas higher levels of ethanol (10–20%, v/v) progressively increased RCT. The temperature at which milk was coagulable by rennet decreased with increasing ethanol content of the milk. The primary stage of rennet coagulation, i.e., the enzymatic hydrolysis of κ-casein, was progressively slowed with increasing ethanol content (5–20%, v/v), possibly due to ethanol-induced conformational changes in the enzyme molecule. The secondary stage of rennet coagulation, i.e., the aggregation of κ-casein-depleted micelles, was enhanced in the presence of 5–15% ethanol, the effect being largest at 5% ethanol. Enhanced aggregation of micelles is probably due to an ethanol-induced decrease in inter-micellar steric repulsion. These results indicate an interrelationship between the effects of ethanol and chymosin on the casein micelles in milk, which may have interesting implications for properties of dairy products.

Biogenic amines (BA) are toxic substances that appear in foods and beverages. Tyramine is the most abundant BA in cheeses. A PCR method was developed to detect the presence of tyramine-producing bacteria during cheese manufacture and ripening. Six different batches of a farmhouse blue cheese were analysed by PCR. Tyramine concentrations were also determined by HPLC. The PCR method was able to anticipate tyramine accumulation in the cheeses; the presence of tyramine-producing microorganisms in the early stages of manufacture correlated well with a high concentration of BA in mature cheese samples.

The protein A encoding gene spa of four Staphylococcus aureus strains isolated from bovine clinical mastitis was amplified by PCR and sequenced. The four strains were selected after an initial screening of spa gene of 41 strains isolated from mastitic cows and were subjected to detailed investigations. According to the sequencing results the spa gene of three strains (M1, M2, M3) appeared with gene segments encoding five (E, D, A, B and C) and four (E, A, B and C) IgG binding domains for two (M1, M3) and one (M2) strain, respectively and with gene segments encoding four, two and two repeats of the octapeptide Xr-repeats for the strains M1, M2 and M3, respectively. For the remaining Staph. aureus strain (M4) gene segments encoding IgG binding domains E, D and A and a new domain BC with a size of 219 bp could be observed. The BC domain appears, with a deletion of a 123 bp segment from the border region between both domains, as fused domain of both previously characterized domains. The Xr-region of this strain had 11 octapeptide repeats.

Four multiparous Holstein cows, each equipped with a duodenal cannula and an ultrasonic mammary blood flow probe, were assigned to a 4×4 Latin square to measure the effects of duodenal infusions of Leu (0, 40, 80 and 120 g/d) on lactational responses and mammary metabolism of nutrients. Cows were fed a diet of 67·0% corn silage, 5·3% grass hay, 14·2% peas, 7·8% maize starch, 1·0% each of molasses, urea, and sodium bicarbonate and 2·4% minerals and vitamins. Requirements of the remaining 9 essential amino acids were met by infusing into the duodenum 323 g/d of a mixture of amino acids including, Ile, Val, Met, Lys, Trp, Phe, His, Thr, Arg, Tyr and Glu. Milk protein content and yield were highest with 40 g/d of Leu and then progressively declined. Milk fat content and yield were significantly decreased over the entire range of Leu infusions. Arterial concentrations of Leu increased linearly and corresponding mammary arterio-venous differences increased to a plateau with 80 g/d of Leu. As Leu infusions increased, extraction rates of Leu decreased linearly, whereas those of Ile, Val, Lys, Arg, Thr and Tyr were significantly increased. Leu was taken up by the mammary gland according to milk output with 0 and 40 g/d of Leu infused and then largely in excess. Based on responses of protein yield and mammary uptake to milk output ratio, Leu concentration in total amino acids absorbed in the small intestine needs to be close to 8·9% for optimal milk protein synthesis.

Organophosphorus pesticides (OPPs), widely used in agriculture, can cause toxic effects to humans and animals. The main purpose of the present work was to determine the contamination in raw milk by the main organophosphorus pesticides used in Italy and to evaluate the opportunity to start specific procedures of risk management along the milk production chain. The samples, collected in 4 Italian dairy plants directly from the tank trucks during the delivering, were representative of 920 tonnes of raw milk. The isolation of the OPPs (acephate, chlorpyriphos, chlorpyriphos-methyl, diazinon, methamidophos, methidathion, phorate, pirimiphos-methyl) was performed by liquid partition followed by clean-up with solid phase extraction. The analyses were carried out by dual column gas chromatography using two nitrogen-phosphorus detectors. Among the 135 samples analysed, 37 were positive in traces and 10 showed an OPP contamination ranging from 5 to 18 μg/kg. The higher results were recorded in the samples collected during the autumn-winter period. The main pollutants detected were acephate and chlorpyriphos. In every positive sample found, the OPP contamination was lower than the maximum residue level (MRL) fixed by the European Commission.

The aim was to investigate the interdependence of udder quarters within cow towards the incidence of intramammary infections during the dry period in herds under selective dry-cow antibiotic therapy. A total of 368 cows among 28 herds were included in a survey. Quarter milk samples collected at the last milking before drying-off and on day 3 after calving were submitted to microbiological procedures. An expected distribution of cows according to their number of newly infected quarters was calculated based on a binomial probability distribution from the overall quarter incidence (or from the quarter incidence in each herd) and compared with the observed distribution. Incidence of newly infected quarters ranged from 0·0 to 39·3%, depending on the herd (median: 17·7%). Interdependence of quarters towards new infection during the dry period was observed whatever the pathogen type, for both treated and untreated cows. Calculation of an expected distribution of cows according to their number of newly infected quarters using the quarter incidence in each herd (instead of the overall quarter incidence) reduced the distance to the observed distribution, but interdependence was still observed. Our results support the application of selective antibiotic therapy at the cow level rather than at the quarter level.

In studies of bovine mastitis, it has been repeatedly confirmed that milking is associated with entrance of microorganisms into the mammary gland (International Dairy Federation, 1987; Bramley, 1992). As different husbandry practices apply between cattle and dairy sheep (cows are machine milked, ewes are usually hand milked), results from cows may not always apply to ewes. The objective of this investigation was to determine whether there were differences in bacterial flora populations in the teat duct and mammary secretion of ewes before and after milking.

The gastrointestinal tract is a complex and dynamic ecosystem. Commensal microorganisms (C), which proliferate in the intestine from birth, are crucial for gut homeostasis while non commensal (NC) microorganisms are transient and enter the organism from the environment and foods. We studied comparatively the influence of oral administration of C and NC Lactobacillus fermentum and Lactobacilus acidophilus on the gut-associated lymphoid tissue (GALT) of conventional mice. To determine the importance of the selection of probiotic host-specificity bacteria with immunomodulating capacity, we examined the interaction with the gut by transmission electron microscopy and FITC-labelled bacteria. We compared the immunomodulation capacities of C and NC strains by studying the number of IgA secreting cells and cytokine profile. No differences were found in the number of IgA+ cells; however, the pattern of cytokine response to C and NC bacteria was different. With regard to proinflammatory cytokine (IFNγ and TNFα), we found that TNFα was mainly produced by NC bacteria, while C bacteria were able to elicit mainly IFNγ. The regulatory cytokines (IL-10 and IL-4) were induced with different patterns for both C and NC strains. No differences in the pathway of internalization to the gut between C and NC were found. In summary, we determined that C and NC bacteria interact with the intestine in the same way; both C and NC bacteria were able to reinforce the surveillance of the gut mucosal immune system. The cytokine profile showed that C bacteria would be involved in the regulation of intestinal homeostasis rather than in the immune activation as the NC bacteria.

Supplementation with a high dose (600 g/d) of rumen inert conjugated linoleic acids (RI-CLA) inhibits milk fat synthesis in total mixed ration (TMR)-fed dairy cows immediately post partum. However, effects of RI-CLA on milk fat and bioenergetic parameters during the transition period in grazing cows have not been investigated. Multiparous Holstein cows (n=39) grazing pasture were randomly assigned to one of three treatments: (1) pasture (PAS), (2) PAS+540 g/d Hyprofat (palm oil; HYPRO) and (3) PAS+600 g/d RI-CLA. HYPRO and RI-CLA supplements were isoenergetic, fed twice daily at 7.00 and 16.00 and provided 0 and 125 g CLA/d, respectively. Treatments began 27±10 d prepartum and continued until 36±1 days in milk (DIM). There was little or no overall effect of RI-CLA on content or yield of milk protein and lactose. RI-CLA supplementation decreased overall milk fat content and yield with RI-CLA-induced milk fat depression (MFD) becoming significant by day 3 when compared with PAS and by day 6 when compared with HYPRO. MFD continued to increase in severity during the first 24 d post partum after which MFD reached a plateau (~40%; RI-CLA v. HYPRO). Pasture-fed cows produced less milk (19·4 kg/d) than the lipid-supplemented groups and although there were no overall differences in milk yield between RI-CLA and HYPRO (22·3 kg/d) a curvilinear relationship (R2=0·57) existed between the RI-CLA-induced milk yield response and extent of MFD. RI-CLA tended to increase milk yield (1·8 kg/d) compared with HYPRO until MFD exceeded 35% (~day 21), after which point the positive milk yield response was eliminated. Milk fat trans-10, cis-12 CLA content averaged 0·25 g/100 g in the RI-CLA treatment, was temporally independent, and was undetectable in PAS and HYPRO treatments. Based on the milk fat 14[ratio ]1/14[ratio ]0 ratio, RI-CLA decreased the overall Δ9-desaturase system compared with PAS and HYPRO. Compared with HYPRO, RI-CLA had no effect on plasma glucose, insulin, leptin, or NEFA concentrations. Results indicate that a high RI-CLA dose decreases milk fat synthesis and tends to increase milk yield immediately post partum in pasture-fed cows; however, excessive MFD (>35%) appears to be associated with a diminished milk yield response.

An examination of the economic impacts of reduced milk production associated with Johne's disease on Johne's-positive and Johne's-negative dairy operations indicated that, if Johne's disease had not existed in US dairy cows in 1996, then the economic surplus of Johne's-negative operations would have been $600 million±$530 million lower, while the economic surplus of Johne's-positive operations would have been higher by $28 million±$79 million, which was not significantly different from zero. The data available for projecting changes in surplus were not sufficiently precise to allow an exact statement on whether Johne's-positive operations would have been better or worse off economically, in terms of the value received for producing more milk if they had not been affected by Johne's disease. The changes in producer surplus, based upon eliminating specific epidemiological risk factors for Johne's disease, were disaggregated between Johne's-positive dairy operations exposed to the risk factor and all other US dairy operations. Eliminating the risk factor of having any cows not born on the operation would have had a significant positive effect on the economic surplus of Johne's-positive operations that had any cows not born on the operation.