Is there a special mechanism behind the changes in somatic cell and polymorphonuclear leukocyte counts,and composition of milk after a single prolonged milking interval in cows?

Background

A single prolonged milking interval (PMI) e.g. after a technical stop in an automated milking system is of concern for the producer since it is associated with a short-lasting increase in milk somatic cell count (SCC), which is a major quality criterion used at the dairy plants. The content of polymorphonuclear leukocytes (PMN) and how the milk quality is influenced has not been much investigated. The SCC peak occurs without any obvious antigen challenge, possibly indicating a different leukocyte attraction mechanism after a PMI than we see during mastitis.

Methods

Composite cow milk samples were taken at the milkings twice daily during 7 days before and 5 days after a PMI of 24 h. Milk was analyzed for SCC, PMN, fat, protein and lactose, and at some occasions also casein and free fatty acids (FFA).

Results

During the PMI the proportion of milk PMN increased sharply in spite of marginally increased SCC. The peak SCC was not observed until the second milking after the PMI, in the afternoon day 1. However, the peak SCC value in morning milk did not occur until one day later, concomitantly with a decrease in the proportion of PMN. After declining, SCC still remained elevated while PMN proportion was decreased throughout the study as was also the milk yield, after the first accumulation of milk during the PMI. Milk composition was changed the day after the PMI, (increased fat and protein content; decreased lactose, whey protein and FFA content) but the changes in the following days were not consistent except for lactose that remained decreased the rest of the study.

Conclusion

The PMI resulted in increased SCC and proportion of PMN. Additionally, it gave rise to minor alterations in the milk composition in the following milkings but no adverse effect on milk quality was observed. The recruitment of PMN, which was further enhanced the first day after the PMI, appeared to be independent of milk volume or accumulation of milk per se. Hence, we suggest that there is a special immunophysiological/chemoattractant background to the increased migration of leukocytes into the milk compartment observed during and after the PMI.     

The effect of pasture turnout on milk somatic cell count,polymorphonuclear leukocytes and milk composition in cows housed in tie stalls

Abstract

This study investigated milk somatic cell count (SCC), polymorphonuclear leukocytes (PMNs) and milk composition in dairy cows, which were kept in tie stalls, during the first days after pasture turnout. Thirty-five cows of the Swedish Red Breed, free of clinical signs of mastitis and with a geometric mean of SCC 67 × 10³ cells/mL, were turned out to pasture after the morning milking on day 0 and then monitored for the next five days on pasture. Samples of cow composite milk were taken at every milking and analysed for SCC, PMN percentage of the total SCC and milk composition. There was a marked increase in both PMN proportion and SCC with the highest SCC value during the study recorded at the evening milking on day 0. The highest value in morning milk was observed on day 1. Milk SCC values in evening and morning milk declined after day 0 and day 1, respectively, but remained on a higher level compared with before turnout to pasture. Milk composition was only slightly altered. Since the changes in SCC and milk composition were of low magnitude, although statistically significant, these effects of pasture turnout can be considered as of minor importance for the milk quality.     

Estimation of daily milk yield of Nellore cows grazing tropical pastures

Beef cows’ milk yield is typically determined by measuring milk yield once daily and then doubling this value to estimate daily production. However, it is not known whether this is accurate. Thus, we aimed to determine the association between morning and afternoon milk yield in grazing Nellore cows. Eighty Nellore cows were used, with initial weight of 516.0?±?1.0 kg. The experiment was a completely randomized factorial scheme, with 20 replications and four treatments (i.e., +?or ??pre-partum supplementation in combination with +?or ??post-partum supplementation): PRMM—1 kg of supplement/cow/day for 90 days pre-partum; MMPS—1 kg of supplement/cow/day for 90 days post-partum; PRPS—1 kg of supplement/cow/day for 90 days pre-partum and 90 days post-partum; and MM—only mineral mix ad libitum during pre- and post-partum. Milk was sampled on days 45, 135, and 225 post-partum (early, middle, and late lactation, respectively). No effects were observed of pre- and post-partum supplementation on milk yield (P?>?0.05). The afternoon/morning proportion of 0.45 in the early third of lactation was higher than other stages, which had a proportion of 0.41 (P?<?0.05). Post-partum supplementation increased milk protein in the morning and afternoon milking (P?<?0.05). There was also no effect of pre- and post-partum supplementation on afternoon-morning proportion other milk components (P?>?0.05). We conclude that estimating daily milk production of grazing beef cattle by multiplying a once daily milking amount times two is not accurate. Under the conditions of this study, proportion of total daily production represented by the ratio of afternoon/morning milking was 0.45 in early lactation (first third) and 0.41 in mid- and late lactation.     

Effect of setting a maximum milking time,from peak lactation,on production,milking time and udder health

Abstract

AIM: To examine the effect of setting a maximum milking time, from peak lactation until drying-off, on production, duration of milking, and udder health of dairy cows.

METHODS: Forty cows were assigned in twin-pairs to be either milked until cups were removed at a milk flow-rate threshold of 0.35 kg/minute (Control), or until cups were removed at a milk flow-rate threshold of 0.35 kg/minute, or maximum time, whichever came first (MaxT). The maximum time was set by determining the milking time of the 70th percentile cow when ranked from fastest to slowest, irrespective of yield. The milking routine was typical of that practised on dairy farms in New Zealand, and involved no pre-milking preparation. The study began at peak lactation (68 (SD 7) days in milk; DIM) and continued for 26 weeks. Duration of milking and milk yield were measured for each milking. Composition of milk was determined from weekly herd tests, and milk quality from fortnightly somatic cell counts (SCC). Completeness of milking and teat condition were assessed during the study. The bacterial status of quarter milk samples was determined at the beginning and end of the study, and all treated cases of clinical mastitis recorded. ANOVA was used to examine the effect of treatment group on variables of interest.

RESULTS: Total milk, fat and protein yields during the study period did not differ between treatments. On average, 30.3% of the morning and 27.6% of the afternoon milkings of MaxT cows reached the maximum time at which cups were removed, and were therefore shortened. While the average milking time of the slowest-milking cow was longer for the Control compared with MaxT group in Weeks 1–18, the average milking time did not differ between treatments. There was no difference in overall SCC, and the incidence of clinical mastitis, or the percentage of infected quarters at drying-off, was similar for the MaxT and Control cows.

CONCLUSION: The results show that setting a maximum milking time can reduce the milking time of slower-milking cows in a herd without compromising overall herd production and udder health.

CLINICAL RELEVANCE: Although the numbers of cows in the study were small there was no evidence of a major increase in SCC, or subclinical or clinical mastitis when a maximum milking time was set for slower-milking cows.     

Lactation curve and effects of milking regimen on milk yield and quality, and udder health in Martina Franca jennies (Equus asinus)

Three experiments were conducted on Martina Franca jennies. Experiment 1 tested Wood's model for evaluating the lactation curve. Data from the entire lactation period of 12 jennies were used. The results showed that Wood's model was able to recognize the shape of the lactation curve from pooled data (r(2) = 0.11; P < 0.01), with the lactation peak occurring at 48 d. Individual curves showed wide variability. Experiment 2 aimed to evaluate the effects of the daily number of milkings (1, 3, or 6) and the interval between the separation of foals from dams and milking (2 or 3 h) on milk yield and udder health. Four groups of jennies (n = 5) were considered: 1 × 3H, milked once per day (1×) with a 3-h interval from the time of foal removal (3H) from the dams to mechanical milking (3-h interval); 3 × 3H, milked 3 times per day with 3-h intervals; 3 × 2H, milked 3 times per day with 2-h intervals; and 6 × 2H, milked 6 times per day with 2-h intervals. The milk somatic cell count (SCC) was monitored. Better efficiency was observed for 3 vs. 1 milking per day and for 3-h vs. 2-h intervals. The regimen of 6 daily milkings at 2-h intervals did not increase milk yield and was related to an increase in the SCC compared with 3 daily milkings. In Exp. 3, the effects of the interval from foal removal to milking (3, 5, or 8 h) on yield, gross chemical composition, organoleptic characteristics of the milk, and udder health of the jennies were evaluated. The effects of milking time were also evaluated. Twenty jennies milked twice daily (2×) were subdivided into 4 groups (n = 5): 2 × 3H, with milkings at 1200 h and 1900 h and an interval of 3 h; 2 × 5H, milked at 1200 h and 1900 h with a 5-h interval; 2 × 8H(1), milked at 1200 h and 2200 h with an 8-h interval; and 2 × 8H(2), milked at 0700 h and 1900 h with an 8-h interval. Milk yield was greater by 28.4% when an 8-h interval was used compared with a 3-h interval and at the morning vs. the evening milking. The milk yield per milking was greatest at 0700 h, indicating the existence of a circadian rhythm in milk secretion processes. Intervals of 5 and 8 h caused significant decreases in the fat and lactose content and organoleptic characteristics of the milk, whereas an 8-h interval led to an increase in the SCC. In conclusion, a milking regimen of twice-daily milking at 0700 h and 1900 h with an 8-h interval provided the maximum yield per day. In terms of milk quality, a 3-h interval yielded the best results.     

Serum amyloid A in the serum and milk of ewes with mastitis induced experimentally with Staphylococcus epidermidis

Mastitis was induced experimentally in ewes with Staphylococcus epidermidis, and the concentrations of serum amyloid A (SAA) in milk and serum, and the somatic cell counts and bacteria in the milk were determined for up to 10 weeks in two experiments, each examining five infected and five control ewes. The somatic cell counts peaked eight hours after infection and preceded an increase in SAA in milk. A maximum concentration of 6460 microg/ml SAA was recorded in milk from the infected sheep, compared with a mean concentration of 1.4 microg/ml in the control sheep. The mean peak concentration of SAA in serum (206.8 microg/ml) occurred earlier (one day after infection) than in milk. The serum concentration of SAA in the healthy animals ranged from 0 to 29.4 microg/ml. There was no correlation between the concentrations of SAA in serum and milk.     

Aetiology of reduced milk ejection in cows after transport and the use of a long-acting analogue of oxytocin for prophylaxis

Milk flow was recorded in 21 cows for three days after they were admitted to a large animal hospital. When the spontaneous flow of milk had stopped, a physiological dose (1 iu) of oxytocin was administered intravenously. Five of the cows were, in addition, treated with 0.35 mg of a long-acting analogue of oxytocin (carbetocin) one hour before the first milking after they were admitted. In the 16 cows not treated with carbetocin, only about 30 per cent of the total milk yield was released spontaneously on the first day, and the injection of 1 iu of oxytocin released approximately another 60 per cent of the total milk yield. On the second day, the proportion of the total milk yield released spontaneously increased and the fraction released after the injection of 1 iu oxytocin decreased. In contrast, the five cows treated with carbetocin released on average 94 per cent of the total milk yield spontaneously during the first milking.     

Effect of vacuum level on milking efficiency, somatic cell counts (SCC) and teat end wall thickness in ewes of Greek mountain Boutsiko breed

The aim of this work was to determine the effect of vacuum level of machine milking on milk yield, milk composition, milking efficiency, somatic cells counts (SCC), and teat end thickness of the Greek mountain breed Boutsiko ewes. Seventy two ewes after a suckling period of 45 ± 5 days were divided into three equal groups of 24 animals for level of milk production, prolificacy and lactation number. The overall experiment lasted 14 weeks. All groups were milked with a pulsation rate of 120/min, pulsator ratio of 50/50, and three vacuum levels of 38, 44 and 50 kPa, respectively, were applied for the three groups. Every two weeks, in a.m. and p.m. milking, measurements were taken for machine milk (MM) and machine stripped milk (MSM), milk composition, SCC, milk emission characteristics (only in a.m. milking) and teat end wall thickness (TEWT) before and after milking. The results have shown that the lower vacuum level of 38 kPa increased (P < 0.05) the percentage of machine milk (82.9%). There were no significant differences among the groups for milk composition, milk flow rate and SCC, but there was a difference in log SCC (P < 0.05) between 38 and 50 kPa. The teat end wall thickness was lower at the lower vacuum level (38 kPa) after milking, and increased (P < 0.001) as the vacuum level was raised to 50 kPa. The findings of this study suggest that with a lower vacuum level of 38 kPa, the ewes are milked better than those with 44 or 50 kPa. Also, the irritation of teats is considerably reduced, while no differences were seen regarding the health of the udder.     

Effects of feeding management and time of day on the occurrence of self-suckling in dairy goats

The occurrence of self-suckling was recorded in 21 dairy goats during periods of 20 minutes at three different times per day (immediately after milking and the first feed, immediately after the second feed and in the afternoon) for 27 days (divided into three experimental periods of nine days). As expected, negative associations between milk yield and the frequency of self-suckling were observed (P<0.05). Goats suckled on their own right teat more frequently than on the left teat. The width of the right teat (measured at the middle of the teat) was positively associated with the frequency of self-suckling after controlling for the width of the left teat. A higher self-suckling frequency was observed immediately after milking than in the other two periods of the day. The frequency of self-suckling by each goat was reduced when animals were supplemented ad libitum with wheat straw in addition to their ordinary feed.     

Effects of tryptophan supplementation on plasma tryptophan and related hormone levels in heifers and dairy cows

This study was conducted to investigate the effects of rumen-protected tryptophan (125 g tryptophan per day) in heifers and dairy cows. Blood samples from dairy cows and heifers were collected for 24h in 3-h intervals on the day before tryptophan supplementation, on day 2, 5 and 7 of tryptophan supplementation, and in heifers additionally on d 14 after tryptophan supplementation was ceased. Plasma tryptophan, melatonin, serotonin, and prolactin concentrations were determined. Tryptophan plasma concentrations on d 5 were augmented at day (11:00 h) and nighttime (02:00 h), (P<0.05) in response to tryptophan supplementation in heifers by 119% and in dairy cows by 47%, respectively, as compared with d 0. Melatonin increased (P<0.05) in response to tryptophan supplementation in heifers, but not in cows. The effect of tryptophan supplementation on plasma tryptophan and melatonin was reversible as demonstrated in heifers on d 14 after cessation of tryptophan supplementation. Serotonin and prolactin in plasma did not respond to tryptophan supplementation. However, milk yield during morning milking increased significantly in tryptophan supplemented cows on d 1, 3 and 4 as compared to the day before tryptophan supplementation. Additional blood samples were taken during afternoon milking in cows at 1-min intervals for the analyses of oxytocin and prolactin on the day before the start and on d 7 of tryptophan supplementation. Milk flow curves were recorded during milking. No effect of tryptophan supplementation on the milking related release of oxytocin and prolactin and on any characteristic of milk flow was observed. In conclusion, tryptophan supplementation caused increased plasma tryptophan in cows and heifers and plasma melatonin in heifers. However, plasma serotonin, prolactin and oxytocin release in cows remained unchanged by tryptophan supplementation. Milk yield at morning milking increased slightly and transiently in response to tryptophan supplementation.     

福建黄兔泌乳性能初探

用本所兔场自繁的１１只福建黄兔健康经产母兔，进行泌乳性能测定。结果表明，本品种的泌乳高峰期出现于产后第９天，第１５天达到高峰，最高日泌乳量１１０．９克，３０天泌乳量２５１１．８克，日平均泌乳量８３．７３克，泌乳力９２５．６克。仔兔适宜补料诱食期应在产后第１５天。     

Effects of short period frequent milking on milk yield and udder health in Turkish Saanen goats

The major purpose of this study was to investigate whether increasing milking frequency for a short period (21 days) increases milk yield and milk components and improves udder health throughout lactation in Turkish Saanen goats. Two groups were formed (control, n = 14, treatment, n = 14); balanced by parity, bodyweight and birth type to make them homogenous. Feeding and management practices were the same for both groups. The treatment group was milked four times a day (4×) for 21 days after weaning whereas the control group was milked twice a day (2×). All the animals were milked twice daily thereafter. The pyronin methyl green stain method was used to estimate the somatic cell count (SCC), which is an indication of udder health. This method provided a count that excluded RNA and background noise while including cells with DNA. Repeated measures analyses indicated that overall differences between the 2× and 4× groups were significant for the morning, evening and total test day milk yields, in that values for the 4× group were increased 14.7, 8.8 and 12.1%, respectively. Differences between the groups for SCC were not significant. The results of this study indicate that increasing milking frequency to 4×, even for a short time (21 days), increases overall milk yield throughout lactation in dairy goats.     

Effect of exogenous prolactin administration on lactational performance of dairy cows

Eight Holstein cows were utilized to examine the effect of prolactin on lactational performance prior to peak milk production (day 21–34 postpartum) and after peak milk production (day 60–73 postpartum). During each 14 day period, cows received daily intramuscular injections of pituitary-derived bovine prolactin (120 mg; 13.0 IU/ mg protein) or excipient. Cows were housed in a controlled environment at 18.1C, 47.8% relative humidity and a 15 hr light: 9 hr dark cycle. In cows administered exogenous prolactin, circulating prolaction concentrations increased within one-half hr post injection, peaked within 2 to 6 hours and declined through the remainder of the day. Average prolactin concentration in the plasma was increased 2 to 5 fold over the 24 hr period in response to prolactin treatment. Yields of milk and milk components (fat, lactose and protein) were not affected by prolactin treatment in either period but the concentration of -lactalbumin in milk was significantly increased (P<.10) in both periods. Circulating concentrations of somatotropin, triiodothyronine, thyroxine, glucagon, nonesterified fatty acids and glucose were not altered. In prolactin-treated cows, the milking-stimulated prolactin release was decreased at both the PM milking, when circulating concentrations of prolactin were high, and the AM milking, when prolactin concentrations had returned to baseline. Concentration of prolactin in milk tended to increase but was not significantly altered by administration of exogenous prolactin. However, prolactin concentrations in plasma were correlated (r=.56) with milk concentrations. It is clear that postpartum administration of exogenous prolactin during the period of lactation prior to peak milk yield or after peak milk yield does not alter lactational performance in high producing dairy cows.     

The interrelationships between milkability traits and subclinical mastitis in cows

The investigation was conducted during 2005-2006 on 4010 dairy cows. Having performed statistical data analysis, we determined that the lowest somatic cell count (SCC) in Red and Red-White cow population was obtained when the milking time was 5-6 min., milking speed was higher than 1.5 kg/min., high milk flow was from 2.51 to 4 kg/min., and in Black-White cow population having a milking time was higher than 7 min., milking speed was from 1.01 to 2 kg/min., a high milk flow --from 2.01 to 4 kg/min. (p<0.001). In Red and Red-White cow population with subclinical mastitis, milking time was longer and milking speed was slower than in healthy cows. High milk flow values were least in healthy Black-White cow population. This determines a more equal milk flow which is desired in milking cows mechanically. Most sensitive to udder infection are 1st lactation cows which have a higher milk flow. A larger phenotype correlation coefficient in Red and Red-White cow population was between the SCC and milking time (-0.089, p<0.01) and between high milk flow (0.086, p<0.01) and milk yield (-0.071, p<0.05). However in Black-White cow population, correlation was found between SCC and milk yield (-0.117, p<0.01) and milking speed (-0.110, p<0.01). Contagious mastitis pathogens were identified in Red and Red-White cow milk samples primarily from productive cows having a milking speed of 1.01-1.5 kg/min., and in Black-White cow population having a milking speed of 1.51-2.0 kg/min.     

Association of automatic milking systems milking frequency in primiparous and multiparous cows with their yield and milkability

The aim of the study was to determine the association of automatic milking systems milking frequency (≤2.40, 2.41–2.80 and >2.80 times/day) in primiparous and multiparous cows with their daily milk yield and milkability. The analysis included of the milk production level and the interaction between milking frequency per day and daily milk yield. Regardless of the daily production level, most primiparous cows were milked 2.41–2.80 times/day and most multiparous cows >2.80 times/day. Higher daily milk yield and a more favourable effect of increasing milking frequency on this parameter were observed in multiparous cows, with an increase from 29.7?kg (milking frequency ≤2.40 times/day) to 31.1?kg milk (>2.80 times/day). In primiparous cows, this increase was smaller and amounted to 0.8?kg milk (from 29.2 to 30.0?kg).     

Serum amyloid A isoforms in serum and milk from cows with Staphylococcus aureus subclinical mastitis

Serum amyloid A proteins (SAA) are very sensitive acute phase proteins, displaying multiple isoforms in plasma and different body fluids. They are currently under investigation as biomarkers of diseases. The aim of the present study was to compare the concentration and isoform expression of SAA in serum and milk of cows with bacteriologically negative milk (control group) and naturally occurring Staphylococcus aureus (S. aureus) subclinical mastitis (subclinical mastitis group). Somatic cell count (SCC) and bacteriological analyses were performed to establish the control and subclinical mastitis group. SAA concentration was evaluated using a commercial ELISA kit, while expression of different isoforms (serum A-SAA and milk M-SAA3 isoforms) was visualized by denaturing isoelectrical focusing and immunoblotting. The SAA concentrations in sera and milk of cows in the subclinical mastitis group were three and 100 times higher than in those from the control group of cows, respectively. Cows in the subclinical mastitis group had more acidic SAA isoforms in serum with the most prominent one at pI 5.5. This isoform was not detected in sera from the control group. Milk samples in the subclinical mastitis group contained abundant highly alkaline M-SAA3 isoforms and most of the serum isoforms, except for that at pI 5.5. In the subclinical mastitis group SAA isoforms with equivalent pI as serum isoforms accounted for 20% of the total SAA concentration in milk. There were significant differences in the concentrations and isoform patterns of SAA in serum and milk between the control and subclinical mastitis groups of cows. Also, we demonstrated that serum SAA isoforms were not transferred to milk proportion to their plasma content.     

南方地区荷斯坦牛乳中体细胞数及乳房性状与泌乳性能相关性的研究

对192头成年荷斯坦牛乳中体细胞数及乳房性状与泌乳性能的相关性进行研究,结果表明:乳中体细胞数较高,9月份达到最高水平;乳房性状评分偏低。体细胞数与月产奶量、月乳脂产量及月乳蛋白产量等性状有极显著负相关(p<0.01),与乳脂率和乳蛋白含量无显著相关关系(p>0.05);后乳房宽度与月产奶量、月乳脂产量及乳蛋白产量有极显著正相关(p<0.01)。     

Effect of milking interval on milk yield and quality and rate of recovery during subsequent frequent milking

Forty mid-lactation, pasture-fed dairy cows were used to study the effects of milking interval on milk yield and quality and whether effects could be reversed during a short period of subsequent frequent milking. Following a 2-day pre-experimental period of normal twice-daily milking (TDM), cows were milked again after 6, 12, 18, 24 or 30 h, with each milking interval followed by 24 h of frequent milking (i.e., every 6 h). Milk yield increased linearly until 18 h and then started to plateau. Similarly, milk quality (serum albumin and proteolytic enzyme activity) became adversely affected after 18 h. These changes coincided with increased permeability of mammary tight junctions (TJ), starting after a milking interval of 18 h. A brief period of frequent milking helped restore milk yields to pre-experiment levels, even after the longest milking interval.     

Housing of Norwegian goat herds and associations with milk yield and milk quality

Abstract

Data from a questionnaire regarding housing factors were merged with data from the milk recording databases (herd mean annual milk yield per goat, somatic cell count (SCC) and bulk milk bacterial count), and the material included 235 herds. Associations with housing factors were tested at herd level and at individual goat level. Housing in insulated buildings with no access to outdoor areas during the winter season, expanded metal grating and no use of bedding predominated. None of the housing factors evaluated were significantly associated with milk yield. In herds using water nipples, SCC was lower compared to herds using water bowls. SCC was also lower in herds with milking facilities in separate milking stalls as compared with combined feeding milking stalls in common pens. No significant associations were found between housing factors and bacterial counts, but the counts were lower in herds with high average milk yields per goat.     

Serum amyloid A and TNF alpha in serum and milk during experimental endotoxin mastitis

A cross-over study was conducted to investigate the effect of intramammarily infused lipopolysaccharide (LPS) on the acute phase reaction in early (EL) and in late (LL) lactation. Nine cows received intramammary injections of 100 microg of Escherichia coli 0111:B4 LPS during EL and LL. The severity of each cows systemic and local signs and change in milk appearance were recorded and scored throughout the experiment. Systemic and local signs were found to be more serious in EL cows. Tumor necrosis factor alpha (TNF alpha) was detected in milk but not in serum. Serum amyloid A (SAA) concentrations increased both in serum and in milk. The milk TNF alpha concentrations peaked at 8 h post-challenge (PC). SAA concentrations started to increase at 8 h PC, and peak concentrations were seen at 32 and 48 h PC in milk and serum, respectively. The milk TNF alpha and SAA seemed to be correlated, being on average higher in EL. Serum SAA concentration was not correlated with milk TNF alpha or SAA, nor with the severity of local or systemic signs, but was correlated with changes in milk appearance.