Evaluation of quality changes in udder quarter milk from cows with low-to-moderate somatic cell counts

Much emphasis has been put on evaluating alterations in milk composition caused by clinical and subclinical mastitis. However, little is known about changes in milk composition during subclinical mastitis in individual udder quarters with a low-to-moderate increase in milk somatic cell count (SCC). This information is needed to decide whether milk from individual udder quarters with a moderate-to-high increase in milk SCC should be separated or not. The aim of this study was to determine how milk composition in separate udder quarters is affected when cow composite milk has low or moderately increased SCC levels. Udder quarter and cow composite milk samples were collected from 17 cows on one occasion. Milk yield was registered and samples were analyzed for SCC, fat, total protein, whey proteins, lactose, citric acid, non-protein nitrogen (NPN), lactoferrin, protein profile, free fatty acids (FFAs), lactate dehydrogenase (LDH), proteolysis, sodium and potassium. Bacteriological samples were collected twice from all four quarters of all cows. The cows were divided into three groups depending on their SCC at udder quarter level. The first group comprised healthy cows with four udder quarters with low SCC, <50 000 cells/ml; composition was equal when opposite rear and front quarters were compared. In the second and the third groups, cows had one udder quarter with 101 000 cells/ml < SCC < 600 000 cells/ml and SCC > 700 000 cells/ml, respectively. The remaining udder quarters of these cows had low SCC (<100 000 cells/ml). Despite the relatively low average cow composite SCC = 100 000 cells/ml of Group 2, milk from affected udder quarters exhibited lower casein number, content of lactose and β-casein (β-CN), while the content of whey protein, sodium, LDH and α-lactoalbumin (α-la) were higher compared to healthy opposite quarters. In addition to these changes, milk from affected udder quarters in Group 3 also exhibited lower values of potassium and αs1-casein (αs1-CN) and higher values of lactoferrin when compared to milk from opposite healthy quarters. This indicates that even when the SCC in cow composite milk is low, there might exist individual quarters for which milk composition is changed and milk quality impaired.     

Amount and variation of strip yields collected by a defined hand-milking method after machine milking of Holstein dairy cows

Hand-milking methods to assess the completeness of milking in dairy cows need to be reliable as well as quick to apply in order to avoid delays in group milking parlours. A previous study comparing different methods demonstrated that a defined milking handgrip with a strip frequency of 1 Hz was most suitable to assess the completeness of milk-out in dairy cows. In a first step, the present study aimed to investigate how much milk can be hand-milked by the defined handgrip, strip frequency and within a time limit of 15 s per quarter. In a second step, the question was how many udder quarters of a cow needed to be hand-milked for a reliable prediction of the amount of rest milk in the udder. The experiment comprised 28 German-Holstein cows of one herd. The cows were hand-milked after cluster detachment by an experienced milker using the defined milking handgrip. All four quarters per cow were hand-milked during nine consecutive milking sessions. The strip yield per quarter per 15 s hand-milking (SY15) was collected in four different containers and weighed with a digital scale. Afterwards, the remaining milk of all four quarters was collected and weighed in a fifth container with a maximum volume equivalent to a net weight of 540 g milk. The analysis showed that neither the position of the quarter nor the chronological order, in which hand-milking was carried out, had an influence on SY15. The amount of rest milk in the udder could be estimated best by hand-milking all four quarters.     

Impact of subclinical and clinical mastitis on sensitivity to pain of dairy cows

A total of 90 cows from three commercial farms were used to evaluate the relationship between subclinical mastitis and clinical mastitis and thermal nociceptive threshold. Milk strips from all udder quarters were tested for clinical mastitis with visual inspection of milk and udder alterations and for subclinical mastitis using California Mastitis Test. Milk yield was recorded, milk was sampled and further analyzed for somatic cells count (SCC). Cows were considered healthy when SCC<200 000 cells/ml and no visual alterations in milk and/or udder, with mild subclinical mastitis when SCC>200 000 cells/ml and no visual alterations in milk and/or udder, with moderate subclinical mastitis when SCC>500 000 cells/ml and no visual alterations in milk and/or udder and with clinical mastitis when visual alterations in milk and/or udder were detected. Nociceptive threshold was evaluated with the thermal threshold meter apparatus applied to the rear legs. Thermal threshold (TT) decreased when we compared healthy cows with cows presenting clinical mastitis and tended to decrease when we compare healthy cows with those with moderate subclinical mastitis. TT was lower at the ipsilateral rear leg compared with the contralateral leg to the infected mammary gland. TT linearly decreases as _log10SCC increased and it showed sharp decrease as _log10SCC exceed the value of 6.4. Increase in one unit of _log10SCC increased the odds of low thermal threshold (lower than 55.8°C). Subclinical mastitis might be a welfare issue as it tended to decrease nociceptive thermal threshold.     

Effects of bovine mammary gland biopsy and increased milking frequency on post-procedure udder health,histology, and milk yield

Sixteen cows in early lactation were randomly distributed into two groups in order to evaluate the effects of mammary biopsies and increased milking frequency on tissue characteristics, post-biopsy udder health and histology. One group was milked twice a day (2×) starting on the 2nd day after calving, until 28 days in milk (DIM). The other group was milked four times a day (4×) from two to 21 DIM, and twice a day (2×) from 22 to 28 DIM. On days 2, 7, 14, 21, and 28 postpartum, one fragment of secretory tissue was collected from one mammary quarter at a time. Collections were alternated between the four mammary quarters per collection day. A total of 80 mammary tissue samples were collected. Qualitative and quantitative analyses of the tissues were conducted by histologic examination. Animal health was assessed by observation of feed intake behavior immediately after biopsy, and weight and body condition score before and one week after biopsy. Udder health was assessed daily from calving to 60 DIM with California Mastitis Test (CMT) and by noting alterations in the milk such as blood, milk clots, blood clots, clinical signs of mastitis. Milk composition and somatic cell count (SCC) were analyzed before and after the biopsies. Milk production was evaluated before biopsy, on the day of biopsy, and after the biopsy. An average of 10 fields at 40× magnification was obtained from each sample. There were no evident changes in mammary morphology as a result of milking two or four times/day at any of the evaluated time points. Biopsy wounds healed rapidly without infection. Intramammary bleeding and CMT alterations were observed in 96% and 75% of the biopsied mammary quarters, respectively. Clinical mastitis was diagnosed in 12% of the biopsied quarters. Different milking frequencies had no effect on the frequency and duration of post-biopsy alterations. Milk production decreased after biopsies done on days 2 for 2× and 4× groups, but it returned to pre-biopsy values within 1 day. Milk composition and SCC were affected transiently. Increased milking frequency did not influence udder health. Post-biopsy recovery was rapid and the procedure proved effective without damaging the cows’ health.     

Response profiles of dairy cows to a single 24-h milking interval in relation with milk proteolysis,udder expansion and immune traits

An extended milking interval of 24 h (24-h milking interval (24h-MI)) constitutes the acute phase of cow adaptation to once-daily milking (ODM). A recent trial including 724 24h-MI challenges demonstrated that milk yield responses to this acute phase of ODM are highly variable (from+22% to −52% of milk yield when switching to the 24h-MI, mean=−25.3%) and that factors such as stage of lactation parity and milk yield level influenced cows’ responses but did not account for all individual variability. Additional traits related to physiological, immune and behavioural adaptation were measured on a subset (96 observations) of this data set. This study aimed to determine (1) the relationship of these traits with cows’ milk yield responses, (2) their ability – combined with previously identified traits – to help predict milk yield responses to 24h-MI (adaptive profiles). The 24h-MI challenge consisted of three successive periods: one control week of twice-daily milking (cTDM), one single day of 24h-MI and then 13 days of TDM (pTDM). Milk yield responses to the 24h-MI (corrected for effects of stage of lactation, parity, milk yield level and milk yield) were related to physiological traits measured during cTDM (milk flow rate, presence or absence of interleukin-8) and to their changes during the 24h-MI (absolute increase in milk flow rate and relative udder distension). Analysis of associations between milk yield responses, stage of lactation, parity, milk yield level, proteolysis, udder expansion and immune traits found three adaptive cow profile clusters. Cows in cluster 1 had a less compliant udder than cows in cluster 2, and they lost more milk during the 24h-MI than cluster-2 and cluster-3 cows. After resuming twice daily-milking (TDM), cluster-2 cows fully recovered the milk they had lost during the 24h-MI. On the opposite, cluster-3 cows did not recover the milk they lost, likely due to udder inflammation during cTDM, as suggested by elevated concentrations of interleukin-8 in their milk. These results combining new traits with stage of lactation, parity and milk yield level constitute a first step towards predicting individual cow responses to a 24h-MI.     

Growth inhibition of Staphylococcus aureus after experimental infection of the udder by high and low concentration of lactoferrin and lysozyme in milk

Ten Holstein-Friesian cows were distributed according to their lactoferrin and lysozyme concentrations in milk into groups with high and low concentrations. In each cow, a front and a rear mammary quarter was infected by inoculation of 10(8) colony forming units of Staphylococcus aureus while the other two quarters were infused with 2 ml of sterile milk. The reaction was observed during the following nine days. After 10 hours the cell count, the lactoferrin and lysozyme concentrations were increased in the infected and control quarters. In milk samples with a high initial lactoferrin concentration the colony forming units of S. aureus were higher than in those with a low concentration. In milk samples with a high lysozyme concentration with colony forming units of S. Aureus were significantly lower than in those with low concentrations. These results show, that the lysozyme concentration in milk of healthy udders could indicate the preparedness for defense against infectious diseases.     

Alteration in the in vitro activity of milk leukocytes during different parity in high yielding cross-bred cows

In vitro activity of milk leukocytes (viz. neutrophils, lymphocytes and macrophages) was evaluated in forty-eight (48) clinically healthy high-yielding cross-bred cows of mid-lactation stage (100–200 days of lactation), divided into four groups namely 1st parity (n = 12), 2nd parity (n = 12), 3rd parity (n = 12) and 4th and above parity (n = 12). Milk samples were taken (250 ml/cow) were taken. Milk somatic cell counts (SCC) and differential leukocyte counts (DLC) were performed microscopically. In vitro phagocytic index (PI) of milk neutrophils and macrophages was evaluated by colorimetric nitro blue tetrazolium reductive assay. Mitogen-induced milk lymphocyte blastogenic response was measured by colorimetric MTT (tetrazolium) assay after isolation of the milk leukocytes by density gradient centrifugation. Milk SCC differed significantly (p < 0.01) between different parity. Cows of 4 and above parity showed significantly (p < 0.01) higher milk SCC compared to primiparous cows. There was no significant difference in milk DLC during different parities in high-yielding cross-bred cows. There was a significant (p < 0.01) variation in lymphocyte blastogenesis amongst parity. The highest value of lymphocyte blastogenesis was seen at 3rd parity, whereas lowest value was obtained in the cows of both 1st and 4th or above parity. PI of milk neutrophils did not differ significantly between parity. PI of milk macrophages was significantly (p < 0.01) higher in 3rd parity and lower (p < 0.01) in 1st and 4th parities. The study indicated that depressed activity of milk lymphocytes and macropages was lower and SCC was higher in the cows of 4th and above parity indicating more mammary stress and hence susceptible to udder infection and mastitis. Therefore, better care and managemental interventions should be taken around these periods.     

Internal teat sealants alone or in combination with antibiotics at dry-off – the effect on udder health in dairy cows in five commercial herds

In the dairy industry, the dry period has been identified as an area for potential reduction in antibiotic use, as part of a one health approach to preserve antibiotic medicines for human health. The objective of this study was to assess the impact of dry cow treatment on somatic cell count (SCC), intramammary infection (IMI) and milk yield on five commercial Irish dairy herds. A total of 842 cows across five spring calving dairy herds with a monthly bulk tank SCC of < 200 000 cells/mL were recruited for this study. At dry-off, cows which had not exceeded 200 000 cells/mL in the previous lactation were assigned one of two dry-off treatments: internal teat seal (ITS) alone (Lo_TS) or antibiotic plus ITS (Lo_AB + TS). Cows which exceeded 200 000 cells/mL in the previous lactation were treated with antibiotic plus ITS and included in the analysis as a separate group (Hi_AB + TS). Test-day SCC and lactation milk yield records were provided by the herd owners. Quarter milk samples were collected at dry-off, after calving and at mid-lactation for bacteriological culture and quarter SCC analysis. Cow level SCC was available for 789 cows and was log-transformed for the purpose of analysis. Overall, the log SCC of the cows in the Lo_TS group was significantly higher than the cows in Lo_AB + TS group and not statistically different to the cows in the Hi_AB + TS group in the subsequent lactation. However, the response to treatment differed according to the herd studied; the log SCC of the cows in the Lo_TS group in Herds 3, 4 and 5 was not statistically different to the cows in Lo_AB + TS group, whereas in the other two herds, the log SCC was significantly higher in the Lo_TS when compared to the Lo_AB + TS group. There was a significant interaction between dry-off group and herds on SCC and odds of infection in the subsequent lactation. The results of this study suggest that the herd prevalence of IMI may be useful in decision-making regarding the treatment of cows with ITS alone at dry-off to mitigate its impact on udder health.     

Real-time evaluation of milk quality as reflected by clotting parameters of individual cow's milk during the milking session,between day-to-day and during lactation

Real-time analysis of milk coagulation properties as performed by the AfiLab™ milk spectrometer introduces new opportunities for the dairy industry. The study evaluated the performance of the AfiLab™ in a milking parlor of a commercial farm to provide real-time analysis of milk-clotting parameters –Afi-CF for cheese manufacture and determine its repeatability in time for individual cows. The AfiLab™ in a parlor, equipped with two parallel milk lines, enables to divert the milk on-line into two bulk milk tanks (A and B). Three commercial dairy herds of 220 to 320 Israeli Holstein cows producing ∼11 500 l during 305 days were selected for the study. The Afi-CF repeatability during time was found significant (P < 0.001) for cows. The statistic model succeeded in explaining 83.5% of the variance between Afi-CF and cows, and no significant variance was found between the mean weekly repeated recordings. Days in milk and log somatic cell count (SCC) had no significant effect. Fat, protein and lactose significantly affected Afi-CF and the empirical van Slyke equation. Real-time simulations were performed for different cutoff levels of coagulation properties where the milk of high Afi-CF cutoff value was channeled to tank A and the lower into tank B. The simulations showed that milk coagulation properties of an individual cow are not uniform, as most cows contributed milk to both tanks. Proportions of the individual cow's milk in each tank depended on the selected Afi-CF cutoff. The assessment of the major causative factors of a cow producing low-quality milk for cheese production was evaluated for the group that produced the low 10% quality milk. The largest number of cows in those groups at the three farms was found to be cows with post-intramammary infection with Escherichia coli and subclinical infections with streptococci or coagulase-negative staphylococci (∼30%), although the SCC of these cows was not significantly different. Early time in lactation together with high milk yield >50 l/day, and late in lactation together with low milk yield<15 l/day and estrous (0 to 5 days) were also important influencing factors for low-quality milk. However, ∼50% of the tested variables did not explain any of the factors responsible for the cow producing milk in the low – 10% Afi-CF.     

Evaluation of blood and milk oxidative status during early postpartum of dairy cows

In dairy cows, the intensity of metabolic activity, associated with the negative energy balance (NEBAL), is responsible for an increased production of reactive oxygen species (ROS) and, subsequently, for the development of the condition of oxidative stress, which may overwhelm the antioxidant potential of the bovine maternal organism, making it prone to the development of many puerperal dysfunctions, as well as to an alteration of colostrum and milk quality. Given these premises, the aims of this study are to evaluate serum and milk concentrations of ROS and lipoperoxides, vitamins A and E, on the 10th, 12th, 14th and 16th day postpartum of dairy cows, a particularly critical period during which the NEBAL reaches its nadir, and to compare the trends of these parameters in two different bovine breeds. The study was performed in pluriparous Italian Friesian and Brown dairy cows. On the 10th day postpartum, all cows underwent a clinical examination to exclude the presence of alterations; furthermore, on the same day, a milk sample was collected from each cow, in order to perform the somatic cell count (SCC; (CE) N. 853/2004) and to establish which of them had an SCC ⩽400 000/ml or >400 000/ml. In this study, among the 110 cows that were initially selected, the evaluation of these parameters allowed the inclusion of 80 animals, which were divided into four groups of 20 subjects each: Group F and F1: Italian Friesian healthy cows, with SCC ⩽400 000/ml and >400 000/ml, respectively; Group B and B1: Italian Brown healthy cows, with SCC ⩽400 000/ml and >400 000/ml, respectively. On the 10th, 12th, 14th and 16th day postpartum, peripheral blood and milk samples were collected. The results obtained show that in group B1 there were higher concentrations of ROS and milk antioxidants compared with Friesian group cows. This datum let us suppose that even in the presence of higher ROS concentrations the antioxidant status found in group B1 seems to be able to counteract the oxidative damage, which is more likely to develop in these cows.     

Use of cow-side progesterone tests to improve reproductive performance of high-producing dairy cows

This study evaluated the effectiveness of the cow-side ELISA milk progesterone test in improving postpartum reproductive performance in the Dordt College dairy herd. Cows that produced more than 18,500 lb of milk per lactation were assigned to the high production group (40 cows), while cows that produced less than 18,500 lb of milk (42 cows) were assigned to the low production group. Twenty-one cows in the high production group and 19 cows in the low production group received no ELISA testing (untreated controls), while the remaining cows in each group were evaluated by ELISA test every 7 d beginning on Day 27 post partum (treated cows). A sequence of 2 high progesterone tests and 1 low test indicated the cows were cycling normally. Cows that had low milk progesterone levels (<5 ng/ml) for 3 consecutive tests were assumed to have follicular cysts and were treated with 2 ml GnRH (Cystorelin, 50 mug/ml). Cows that had 3 consecutive high tests (>5 ng/ml) were assumed to have persistent corpora lutea (CL) and were treated with 5 ml PGF(2)alpha (Lutalyse, 5 mg/ml). In both the high and low production groups, treated cows had higher (P < 0.08) pregnancy rates by Day 210 than the untreated controls (63.2 vs 38.1% and 56.5 vs 42.1%, respectively). The days open were reduced (P < 0.05) for the treated animals by 41.6 d compared with the controls. The treated cows produced a net savings of $70.42 (US) per cow assuming a $3.00 savings/day open.     

Associations between strain,herd size,age at first calving,culling reason and lifetime performance characteristics in Holstein-Friesian cows

Cow longevity and lifetime performance traits are good indicators of breeding effectiveness and animal welfare. They are also interrelated with the economics of dairy herd. Unfortunately, a high milk yield is often associated with deteriorated cow health and fertility and, consequently, with an increased culling rate. This situation, observed also in the Polish population of Holstein-Friesian cattle, inspired us to undertake a study on the associations between some factors and lifetime performance characteristics. The data set consisted of the records on 135 496 cows, including 131 526 of the Black and White strain (BW), and 3970 of the Red and White strain (RW) covered by performance recording and culled in 2012. It was found that cows of the BW strain and those from the largest herds (>100 cows) reached higher lifetime and mean daily energy-corrected milk (ECM) yields than cows of the RW strain and those from smaller herds culled at a similar age. Cows youngest at first calving (<2.0 years) were characterised by the highest lifetime ECM yield. It indicates that heifers can be bred even when they are younger than 15 to 16 months with no significant negative effect on their later performance. Infertility and reproduction problems (39.6%) and udder diseases (15.5%) constituted the most frequent reasons for cow culling. Cow longevity and lifetime productivity were considerably affected by the interactions between the studied factors.     

Economic consequences of mastitis and withdrawal of milk with high somatic cell count in Swedish dairy herds

The main aim was to assess the impact of mastitis on technical and economic results of a dairy herd under current Swedish farming conditions. The second aim was to investigate the effects obtained by withdrawing milk with high somatic cell count (SCC). A dynamic and stochastic simulation model, SimHerd, was used to study the effects of mastitis in a herd with 150 cows. Results given the initial incidence of mastitis (32 and 33 clinical and subclinical cases per 100 cow-years, respectively) were studied, together with the consequences of reducing or increasing the incidence of mastitis by 50%, modelling no clinical mastitis (CM) while keeping the incidence of subclinical mastitis (SCM) constant and vice versa. Six different strategies to withdraw milk with high SCC were compared. The decision to withdraw milk was based on herd-level information in three scenarios: withdrawal was initiated when the predicted bulk tank SCC exceeded 220 000, 200 000 or 180 000 cells/ml, and on cow-level information in three scenarios: withdrawal was initiated when the predicted SCC in an individual cow's milk exceeded 1 000 000, 750 000 or 500 000 cells/ml. The accuracy with which SCC was measured and predicted was assumed to affect the profitability of withdrawing milk with high SCC and this was investigated by applying high, low or no uncertainty to true SCC. The yearly avoidable cost of mastitis was estimated at €8235, assuming that the initial incidence of mastitis could be reduced by 50%. This cost corresponded to 5% of the herd net return given the initial incidence of mastitis. Expressed per cow-year, the avoidable cost of mastitis was €55. The costs per case of CM and SCM were estimated at €278 and €60, respectively. Withdrawing milk with high SCC was never profitable because this generated a substantial amount of milk withdrawal that was not offset by a sufficient increase in the average price per delivered kg milk. It had the most negative impact on net return when high incidence of mastitis was simulated. Withdrawing milk with high SCC based on low-uncertainty information reduced the amount of withdrawn milk and thus resulted in less negative effect on net return. It was concluded that the current milk-pricing system makes it more profitable for farmers to sell a larger amount of milk with higher SCC than to withdraw milk with high SCC to obtain payment premiums, at least in herds with mastitis incidences within the simulated ranges.     

IgG1 variations in the colostrum of Holstein dairy cows

High-immune quality colostrum (IgG1 concentration ⩾50 g/l) is crucial for the health and development of the young calf. Studies on colostrum quality tend to focus on external factors such as breed, parity or dry period length, but few have focused on within-cow variations. Here we ran experiments to gain a deeper insight into within-cow variation in IgG1 concentrations in dairy cow colostrum. Trials were performed in an experimental farm, located in the Western part of France. Colostrum from each quarter and a composite sample (mix of four quarters) were concomitantly collected on 77 Holstein dairy cows just after calving to assess the influence of sample type on IgG1 concentrations. Variation in IgG1 concentrations during the first milking was studied on samples from nine cows collected every minute from the start of milking. Repeatability of colostral IgG1 concentration was estimated from 2009 and 2010 data on 16 healthy cows. IgG1 concentrations were tested using a radial immunodiffusion method. Sensitivity and specificity were similar regardless of sample type tested (individual quarter or composite milk). Mean average IgG1 concentration was 54.1 g/l in composite colostrum, and was significantly higher in hind quarter teats (56.2 g/l) than front quarter teats (53.1 g/l). Average IgG1 concentration did not change significantly during colostrum milking, and the variations observed (15% or less) were likely due to the laboratory method (CV 15%). IgG1 concentrations in dam colostrum increased slightly from 2009 to 2010 due to BW and parity effects. In 56% of cases, colostrum quality could have been assessed on either individual or composite colostrum samples collected at any time during the first milking without affecting the reliability of the measurement. However, in other cases, differences were significant enough to mean that estimates of average IgG1 concentration in colostrum from any one quarter would not be reliable. It is concluded that colostrum quality, from an IgG1 concentration point of view, could be assessed with a composite sample taken at any time during the first milking.     

Effects of different suckling systems on milk production, udder health, reproduction, calf growth and some behavioural aspects in high producing dairy cows - a review

This article discusses the consequences of different suckling systems in the industrial countries for the milk production, udder health, reproduction and behaviour of high producing dairy cows and the effects on the gain, health and behaviour of the calves. The suckling systems are divided into three different categories depending on the purpose and duration of the suckling period. Long-term suckling with or without additional milking covering the period where the calf has a nutritional need for milk, and short-term suckling, where cow and calf are kept together in the colostrum period only.Long-term suckling without additional milking in early lactation can in some situations stimulate the subsequent milk production to a greater extent than milking alone. No clear or significant differences can be found between restricted and free suckling systems. Most experiments show that suckling decreases the risk of mastitis in the suckling period and in some cases even for some time after the suckling has been terminated. Suckling and milking during the same period is not advantageous in production turns because of a very poor ejection of milk. Long-term suckling can increase the post-partum interval until first heat, in some cases until the end of the suckling period. However, as the cows appear to be more fertile, the net effect on reproduction is small. The suckled calves are usually healthy with a high daily gain. Short-term suckling have more advantages than disadvantages on production, health and behaviour of both the cow and the calf compared to an immediate separation after birth.     

Bull exposure and an increased within-day milking to suckling interval reduced postpartum anoestrus in dual purpose cows

It is hypothesized that the combined effects of suckling and milking in the dual purpose cows is one of the main suppressors of reproductive efficiency in this production system. The experiment described here examined whether managing the interval between milking and suckling could reduce the postpartum anoestrous period and whether the presence of a teaser bull could enhance the effects of these managements. The experiment involved 39 Bos taurus x Bos indicus cows which had an average weight of 523.0 +/- 12.8 kg (mean +/- S.E.M.) and body condition score of 5-7 (scale 1-9) at calving. The cows and calves grazed separate pastures and the cows were supplemented with 2 kg 17% CP concentrates and 1 kg molasses per cow per day. The experiment was conducted over the first 100 days postpartum. Cows were hand-milked once per day in the presence of the calf to stimulate milk release. The factors in the 2 x 2 design were the milking to suckling interval (0 h, control suckling; CS versus 8 h prolonged-delay suckling; PDS) and no exposure versus exposure to a teaser bull (B). Cows were assigned at random within calving date to the four treatments: CS (n = 10), PDS (n = 10), CS-B (n = 9) and PDS-B (n = 10). Cows on treatments CS and CS-B had three-quarters of the udder milked and one-quarter was not milked. The entire udder was milked on those treatments where there was an interval between milking and suckling. The bull was introduced 7 days after calving in treatments where the cows were exposed to a teaser bull. Body weights of cows and calves and cow milk yield were recorded. Weekly blood samples were collected for plasma progesterone assay. Data were analyzed by ANOVA in a 2 x 2 factorial design and by chi(2)-test. There were no statistically significant differences between treatments in cow body weight at calving and at 100 days postpartum, nor in milk yield (overall mean 6.0 +/- 1.1 kg per day). Calf daily gain was 598 +/- 25 g for treatments CS and CS-B in which suckling immediately followed milking and 833 +/- 24 g for treatments PDS and PDS-B (P < 0.001). The proportion of cows ovulating was CS 80.0%, PDS 100.0%, CS-B 88.8% and PDS-B 100.0%. The difference between CS and PDS or PDS-B was significant (P < 0.05). CS-B did not differ significantly from the other three treatments. The calving to first ovulation interval was not improved when the interval between milking and suckling was increased from 0 h (56.5 +/- 5.0 days) to 8 h (64.8 +/- 4.5 days). Exposure to a teaser bull, however, significantly (P < 0.001) reduced this interval from 77.0 +/- 2.7 days (no bull exposure) to 44.4 +/- 2.7 days (exposure to teaser bull). Exposure to a teaser bull significantly reduced the calving to first anoestrus interval. Delaying the start of suckling after milking did not improve the reproductive performance of the cows or alter the effect of bull exposure, however, delaying suckling after milking improved the performance of the calves without affecting milk yield.     

Risk factors and milk yield losses associated with lameness in Holstein-Friesian dairy cattle

Weekly locomotion scores on a scale of 1 to 5 were used to investigate the relationship between cattle lameness, management systems and the impact of lameness on milk production. The data were 14026 locomotion scores from 248 Holstein-Friesian cows. Cows were managed in two groups, XE (high-concentrate feed and housed indoors all year) and XM (low-concentrate feed and outdoors in summer). Analysis was performed using residual maximum likelihood. Results indicated that the most significant variables affecting locomotion were time of year when the animal was locomotion scored and management group. Cows scored during February and August had increased locomotion problems. Cows in the more intensively managed group had significantly poorer locomotion compared with those in the more extensive group. Older animals were more susceptible to lameness than heifers. Body weight, body condition score and days in milk (DIM) also accounted for significant variation in locomotion score. Poor locomotion was associated with a significant reduction in the milk yield of later lactation cows. There was a significant difference in the shape of the lactation curve depending on whether or not the cow was lame during lactation. Average persistency was greater for the group of cows never lame throughout lactation compared with those lame before 60 DIM.     

Enzyme activity and acute phase proteins in milk utilized as indicators of acute clinical E. coli LPS-induced mastitis

The importance of non-visual and on-line monitoring of udder health increases as the contact between humans and animals decreases, for example, in robotic milking systems. Several indicator systems have been introduced commercially, and a number of techniques are currently in use. This study describes the kinetics of seven indigenous milk parameters for monitoring udder inflammation in an Escherichia coli lipopolysaccharide (LPS, endotoxin)-induced mastitis model. Proportional milk from LPS-infused quarters was compared with milk from parallel quarters, which were placebo-treated with sterile 0.9% NaCl solution. Somatic cell counts (SCCs), the acute phase proteins (APP), that is, milk amyloid A (MAA) and haptoglobin (Hp), and the enzymes N-acetyl-β-D-glucosaminidase (NAGase), lactate dehydrogenase (LDH), alkaline phosphatase (AP) and acid phosphatase (AcP) were measured at fixed intervals during the period from -2 to +5 days after LPS and NaCl infusions. All parameters responded significantly faster and were more pronounced to the LPS infusions compared with the NaCl infusions. All parameters were elevated in the proportional milk collected at the first milking 7 h after infusion and developed a monophasic response, except Hp and MAA that developed biphasic response. SCC, LDH, NAGase and Hp peaked at 21 h followed by AP, AcP and MAA peaking at 31 h with the highest fold changes seen for MAA (23 780×), LDH (126×), NAGase (50×) and Hp (16×). In the recovery phase, AP, AcP and Hp reached base levels first, at 117 h, whereas LDH, NAGase and MAA remained elevated following the pattern of SCC. Minor increases of the milk parameters were also seen in the neighboring (healthy) quarters. Distinction between inflamed and healthy quarters was possible for all the parameters, but only for a limited time frame for AP and AcP. Hence, when tested in an LPS mastitis model, the enzymes LDH, NAGase and AP in several aspects performed equally with SCC and APP as inflammatory milk indicators of mastitis. Furthermore, these enzymes appear potent in the assessment of a valuable time sequence of inflammation, a necessary ingredient in modeling of programs in in-line surveillance systems.     

Bacteriostatic activity in cow's milk from udders infected with Streptococcus agalactiae and Staphylococcus aureus.

Milk samples from infected udders contained more lactoperoxidase and more thiocyanate than before infection. Irritation of 10 quarters of 5 cows caused the increase in the bacteriostatic activity of milk. Bacteriostatic activity of milk from the udders infected with staphylococci dropped after several weeks of chronic mastitis.     

Effect of milking frequency and nutritional level on aspects of the health and welfare of dairy cows

The objective of this experiment was to investigate the effect of milking frequency and nutritional level on some aspects of animal health. Holstein-Friesian cows (n = 60) were assigned post calving to a factorial arrangement of treatments; twice a day (TAD) milking on a high or low nutritional level; once a day (OAD) milking on a high or low nutritional level. Milking characteristics were recorded daily. Blood samples to evaluate changes in the composition of the blood cells, milk leakage, udder tension and locomotory ability were measured on four occasions. Teat-ends were classified for hyperkeratosis (HK) monthly post partum. TAD had longer daily milking times (P < 0.001) compared with OAD cows. There was no effect of milking frequency or nutritional level on morning milking time, time to milk letdown or peak milk flow rate (P>0.05). High nutritional level cows had higher average flow-rates (P < 0.05) than low nutritional level cows. Neither milking frequency nor nutritional level affected HK (P>0.05). However, HK values were positively correlated with daily milking time for OAD cows for 6 months of lactation (P < 0.05). This correlation was significant (P < 0.01) for cows milked OAD on high nutrition during the peak lactation period. OAD cows had higher levels of milk leakage compared with TAD cows during the month of May (P < 0.01). Cows on high nutrition milked OAD showed higher udder firmness scores than cows milked once or twice daily at the low nutrition level in June and July (P < 0.05). OAD cows had higher locomotion scores compared with TAD cows (P < 0.001). Locomotion and udder firmness scores were significantly correlated for OAD in June (P < 0.05). OAD cows had lower blood lymphocyte counts, numerically higher counts of neutrophil and a higher monocyte count at peak lactation compared with TAD cows suggesting that OAD cows had altered immune responses. The increase in milk leakage, higher udder firmness and locomotion scores in conjunction with changes in blood cells, suggests that OAD milking may have caused some discomfort to the cows during peak lactation. A reduction in the concentrate input to OAD cows during this period could ameliorate this problem.