| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
,
* Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, SE-753 23 Uppsala, Sweden
Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Box 7023, SE-750 07 Uppsala, Sweden
Department of Pigs, Poultry and Ruminants, National Veterinary Institute (SVA), SE-751 89 Uppsala, Sweden
Department of Clinical Sciences, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
1 Corresponding author: Martin.Odensten{at}huv.slu.se
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
|---|
Key Words: dry-off • dairy cow • metabolism • udder health
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
|---|
A common practice in dairy herds with intensive milk production has been to breed cows with the aim of establishing a calving interval (CI) close to 12 mo (Strandberg and Oltenacu, 1989; Brand and Warner, 1997). More recent studies have shown that an extended CI has beneficial effects on high-producing cows because of a better utilization of the milk production capacity (Arbel et al., 2001; Österman and Bertilsson, 2003) and improved fertility, because an extended CI prolongs the time available to resume reproductive functions (Ratnayake et al., 1998) and reduces udder health problems caused by high milk production at DO (Rehn et al., 2000).
During the 2003 Swedish milk-recording year, 46% of the enrolled dairy cows in Sweden were of the Swedish Red and White (SRB) breed, whereas 48% of the cows belonged to the Swedish Holstein (SH) breed (Swedish Dairy Association, 2005). The SRB breed is a dual-purpose breed with slightly lower milk production and lower incidence of mastitis than SH cows (Emanuelson et al., 1993; Swedish Dairy Association, 2005). Our earlier studies on metabolism and health at DO (Odensten et al., 2005a, b) included only SRB. Because there might be breed differences (e.g., in metabolism and in milk production) at DO, it would be relevant to make comparisons between SRB and SH.
An objective of the study was to investigate the effects of daily milk yield just before DO on milk volume reduction and intermediary metabolism during DO. The effects of daily milk yield on udder health during DO and following parturition were also studied. Other aims were to study whether a prolonged CI would facilitate a rapid reduction in milk volume during DO and whether breed (SRB or SH) would affect the outcome.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
|---|
Throughout the experiment, the cows were housed in individual tie stalls with sawdust bedding. Drinking water was available in automatic water bowls, and the cows had free access to salt licks. Body condition scoring was conducted once during the week before DO. Cows were fed individually according to Swedish standards for ME, protein, and minerals (Spörndly, 2003) based on actual milk yield and stage of gestation. Prior to DO, silage, concentrates, and minerals were fed at 0530, 0830, 1300, and 1600 h each day. During the DO period (d 1 to 5), the cows were fed 4 kg of DM/ d as silage and were fed wheat straw ad libitum. Silage refusals were registered during the DO period. After the DO period, the cows were introduced to the dry period feed ration, which was composed according to Swedish standards (Spörndly, 2003). The chemical composition and DM content of the individual feed-stuffs are shown in Table 1
. The cows were milked twice each day (i.e., at 0600 and 1600 h) during lactation and once daily on d 2 and 5 during DO. The Uppsala Local Ethics Committee approved the experimental design.
|
.
Milk.
Measurements of daily milk yield (sum of morning and evening milkings, kg of milk/d), milk composition (fat, lactose, and protein), and SCC (Fossomatic 5000; N Food Electric, Hillerød, Denmark) were taken once 1 wk prior to DO. The same measurements were also made on milk samples taken on 4 occasions during the week before DO, at evening milkings on d –6 and –3, at morning milkings on d –5 and –2 before DO, and at the 2 milkings during DO. Cow composite SCC was also measured once weekly for 4 wk after parturition. Quarter milk samples were collected aseptically after the morning milking twice (2 d apart) for 4 wk prior to DO (PD4), at the 2 milkings during DO, and twice (2 d apart) at 1 (PP1) and 4 (PP4) wk postparturition (PP). All quarter milk samples were analyzed for bacteriological growth using accredited methods at the Section of Mastitis, National Veterinary Institute, Uppsala, Sweden. An IMI was defined as a bacteriological finding of major or minor udder pathogens on at least 1 of 2 sampling occasions per period (PD4, DO, PP1, and PP4). Major pathogens were all udder pathogens other than the minor udder pathogens Corynebacterium bovis and CNS.
Milk Leakage, Teat Condition, and Teat Closure.
During DO, the animals were inspected for milk leakage (i.e., milk observed dripping from one or more teats). In 37 cows, the teat-end condition was scored according to Neijenhuis et al. (2000) once weekly after DO. All teats were examined starting the first week after DO. Five scores (0 = none, A = slight, B = moderate, C = thick, and D = extreme callosity) were used, incorporating both smooth (1) and rough (2) callosity. Teat closure was investigated once weekly after DO in 2 teats (random choice of right or left side) in the same 37 cows according to Dingwell et al. (2004). If both teats were scored as closed for 2 consecutive weeks, the teats were considered permanently closed and no more investigations were performed. The same conditions applied for the examinations of teat-end callosity.
Blood.
Blood samples were collected into evacuated tubes containing sodium heparin as anticoagulant (Venoject; Terumo Europe N.V., Leuven, Belgium). Blood was taken from one of the jugular veins between 0900 and 1000 h on d –4, –2, 1, 3, 5, 8, 10, 12, 15, and 19 in relation to DO d 1. Blood was centrifuged for 8 min at 1,800 x g, and plasma was stored at –20°C until analyzed for cortisol, NEFA, BHBA, urea, glucose, and insulin. Cortisol was analyzed using a commercial kit (Coat-A-Count; Diagnostic Products Corporation, Los Angeles, CA). Enzymatic determinations were used for NEFA (NEFA C; Wako Chemicals Inc., Richmond, VA), glucose (Glucoquant Glucose/HK; Roche Diagnostics, Boehringer Mannheim, Mannheim, Germany), and insulin (Mercodia Ultrasensitive Bovine Insulin ELISA; Mercodia AB, Uppsala, Sweden). The concentration of BHBA was determined using a colometric method (BHBA liquicolor; Stanbio Laboratory, Boerne, TX). Urea was determined on a Technicon Autoanalyzer (Technicon AutoAnalyzer II, Technicon method no. SE40001FD4; Technicon GmbH, Frankfurt am Main, Germany).
Statistical Analysis
Statistical analyses of variance were performed using PROC MIXED (SAS program, version 8.02; SAS Institute, 2001). Least squares means (LSM) were compared with the comparison-wise error rate after a significant F-test. Least significant difference values were based on calculations with t0.975. Values before DO were calculated on individual values and used in the ANOVA for blood parameters according to model 1. The effect of the SRB selection lines, LFI and HFI, was not significant in any of the blood parameters and were therefore not included in the final model for blood parameters. The cows were divided into 3 numerically equal groups, low (LY = 5.0 to 11.4 kg of milk/d; n = 19), medium (MY = 11.5 to 17.7 kg of milk/d; n = 19), and high (HY = 17.8 to 29.5 kg of milk/d; n = 18) yield depending on their daily milk production (mean of 2 test days, each including 2 milkings) in the week prior to DO. The study was carried out over a period of 16 mo, and the cows in each yield group were evenly distributed over this period of time. The distribution of breed, lactation number, and CI in each yield group is given in Table 2. The time factor (Day) was divided into 3 classes (PER 1), defining data as before, during, or after DO. The model used different variances among subjects for the 3 period classes (PER 1) and different autoregressive covariance structures for the within-subject variations. Nonesterified fatty acid values were not normally distributed, and the statistical analysis was performed on the log-transformed values. Interactions were tested and the ones that were not significant were dropped from the model. The interactions Yield x Day and CI x Day were retained in the model to retrieve LSM values:
|
Model 1Class: ID Yield Breed Day Par CI PER 1
Yblood = Yield Breed Day Par CI Yield x Day CI x Day/OUTPRED=N1 DDFM=SAT REPEATED/ SUB=ID TYPE=AR(1) GROUP=PER 1
The daily milk yield, milk composition, and SCC before and during DO were analyzed using model 2. The data were grouped into 2 period classes (before and during DO) before analyses, and different variances among subjects for the 2 period classes (PER 2) and different autoregressive covariance structures for the within-subject variations were used. A separate analysis using model 2 was made for milk SCC postparturition. Because SCC was not normally distributed, log-transformed values were used in the statistical models. The interaction Yield x Day was retained in the model for retrieving LSM values. Calving interval and parity were not significant and were deleted from the final model:
Model 2Class: ID Yield Breed Day PER 2
Ymilkcomp = Yield Breed Day Yield x Day/OUT-PRED=N1 DDFM=SAT REPEATED/SUB=ID TYPE=AR(1) GROUP=PER 2
ID = cow ID
Yield = 3 yield groups; LY, MY, and HY
Breed = breed of the cow (SH or SRB)
Day = sample date (in relation to DO referred as d 1)
Par = parity (primiparous or multiparous cows)
CI = 12 mo and 15 mo
PER 1 = prior to DO, during DO, and after DO
PER 2 = prior to DO, during DO
Differences between yield groups in numbers of IMI (major udder pathogens and all udder pathogens) on cow and udder quarter levels at DP4, DO, PP1, and PP4 were evaluated using Fisher’s exact test (cow level) and 
2 (quarter level; Statistica, StatSoft Inc., Tulsa, OK). Differences in disease incidence, teat closure, and teat-end score were also evaluated using Fisher’s exact test.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
|---|
The milk yield, fat, protein, and lactose contents as well as the P-values from the F-tests of the fixed effects in the model for these parameters are presented in Table 3. The daily milk yield and lactose content decreased, whereas the milk fat and protein content increased during DO in all 3 groups. The rise in milk fat percentage at d 5 was higher (P = 0.001) in the MY and HY groups than in the LY group. The overall fat content was higher (P < 0.001) in SRB/HFI cows than in SRB/LFI and SH cows during DO. Overall, there was an effect of yield on milk lactose, and the LY group had the lowest values.
|
, 2, and 3, and the P-values from the F-tests of the fixed effects in the model for these components are presented in Table 4. Plasma cortisol increased on d 3 during DO, compared with before DO, within each yield group but the increase was not significant in the LY group. After the DO period, the concentrations returned to the same levels as before DO, except in HY at d 8. Overall, the LY group had lower (P < 0.001) plasma cortisol levels than the other groups. Multiparous cows (10.79 ± 0.69 mmol/L) tended (P = 0.05) to have higher concentrations compared with primiparous cows (9.12 ± 0.52 mmol/L).
|
|
|
|
There were no yield effects on plasma insulin and glucose concentrations. The numerically lowest within-group insulin level was found on d 3 in all yield groups, but the insulin level was significantly lower than prior to DO only in the HY group (Figure 2). The CI-15 group tended to have higher insulin levels in plasma before DO than did the CI-12 group (1.12 ± 0.10 ng/mL and 0.93 ± 0.06 ng/mL, respectively; P < 0.001), whereas the plasma glucose concentration was significantly higher in the CI-15 group (3.64 ± 0.06 mmol/L) compared with the CI-12 group (3.39 ± 0.03 mmol/L). The primiparous cows had lower mean values compared with the multiparous cows (3.42 ± 0.04 mmol/L and 3.62 ± 0.05 mmol/L, respectively).
A decrease in plasma urea was observed from d 3 during DO and throughout the study in all yield groups. Plasma urea was affected by parity, with lower values in primiparous cows (3.89 ± 0.11 mmol/L) than in multiparous cows (4.31 ± 0.15 mmol/L). The plasma concentration of BHBA decreased somewhat during the DO period in all groups and remained lower than before DO during the study. Overall, the LY group (0.41 ± 0.02 mmol/L) had lower (P < 0.001) plasma BHBA than did the MY (0.50 ± 0.02 mmol/L) and HY (0.53 ± 0.02 mmol/L) groups. Primiparous cows (0.43 ± 0.01 mmol/L) had lower mean plasma BHBA levels than multiparous cows (0.53 ± 0.02 mmol/L). Breed affected the BHBA concentration, with a higher overall concentration in SRB cows (0.51 ± 0.01 mmol/L) than in SH cows (0.46 ± 0.02 mmol/L).
Disease Incidence
From DO to 2 mo after calving, 11% of the cows suffered from clinical mastitis and 27% suffered from some other clinical disease (mainly puerperal paresis). The disease incidence did not differ among the LY, MY, and HY groups, between breeds, or by CI.
Milk SCC and Bacteriology
Milk SCC prior to and during DO is presented in Table 3. The log SCC increased significantly (P < 0.001) at the 2 milkings during DO, compared with prior to DO, in all groups. The LY cows had higher SCC overall compared with the MY and the HY cows (P = 0.05 and P < 0.001, respectively). The SRB/HFI and SRB/LFI cows had significantly lower log SCC prior to DO compared with the SH cows (P < 0.04 and P < 0.004, respectively). The log SCC decreased again in the 4 weekly samples postparturition in all groups, and the same differences were again found between the breed groups as prior to DO. The overall log SCC/mL for the 4-wk period postparturition were 2.50 ± 0.05, 2.35 ± 0.07, and 2.68 ± 0.06 for SRB/HFI, SRB/LFI, and SH, respectively. There were no differences in log SCC among the yield groups postparturition.
Overall, the proportions of cows with IMI at PD4, DO, PP1, and PP4 were 26.8, 42.8, 39.3, and 23.2%, respectively. The proportion of cows with IMI was significantly lower in LY than in MY (P = 0.039) and HY (P = 0.013) at PP1. The proportions of udder quarters with IMI (all udder pathogens) are presented in Table 5. The proportions with IMI (all udder pathogens) at PD4, DO, PP1, and PP4 were 13.4, 17.8, 18.3, and 8.0%, respectively, with lower (P < 0.05) numbers in LY than in MY and HY at PD4 and PP1. At all time points, minor pathogens were more common than major pathogens. When studying only major pathogens, significantly fewer IMI were found at PP1 in LY compared with MY (P = 0.016) and HY (P = 0.040). Overall, CNS (61/131 diagnoses) was the most common bacteriological finding, followed by C. bovis (33/131). The following major pathogens were found: Streptococcus uberis (11/131), Streptococcus dysgalactiae (7/131), Enterococcus spp. (6/131), Escherichia coli (6/131), Staphylococcus aureus (4/131), Arcanobacterium pyogenes (2/131), and Streptococcus spp. (1/131).
|
. The proportions of cows scored open on at least 1 occasion were 38, 46, and 63% in the LY, MY, and HY groups, respectively. The corresponding proportions of open udder quarters were 11, 17, and 25%. The proportion of open udder quarters was lower (P = 0.047) in LY than in HY, but no other significant differences were found. When conducting each weekly observation (wk 1 to 5), differences were found at wk 2 and 3 after DO. At wk 2, fewer cows (P = 0.046) and udder quarters (P = 0.002) were open in LY cows than in HY cows, whereas fewer cows (P = 0.036) and udder quarters (P = 0.014) were found open in LY than in MY at wk 3. The proportion of cows or quarters with IMI at PP1 did not differ between cows or quarters that were scored as closed on all occasions and cows that were scored as open.
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
|---|
In the present study, only MY and HY cows had elevated plasma cortisol concentrations during DO. We previously observed that cows fed only straw during DO had higher cortisol levels in blood than cows fed straw plus 4 kg of DM/d as silage, which may have been due to a more pronounced negative energy balance in the group fed straw only (Odensten et al., 2007). However, in early-lactation cows the degree of negative energy balance is not related to the plasma level of cortisol (Beerda et al., 2004). It is possible that the elevated cortisol levels in the present study were related to a higher intramammary pressure in cows with a higher milk production at DO. In HY cows, the cortisol level was elevated also at 2 d after the end of the DO period. At this time, the differences in energy balance should have been negligible, but the intramammary pressure may still have been significant. However, a relationship between cortisol and energy balance cannot be ruled out because the HY cows were assumed to be in a lower energy balance during the DO period.
In agreement with a previous study (Odensten et al., 2005a), lactose secretion decreased markedly in milk during DO, whereas the drop in secretion of milk protein and fat was less prominent. The drop in lactose concentration has been shown to occur concomitantly with an increased concentration of Na in milk (Stelwagen et al., 1994). Most probably, the Na concentration in milk increased during DO in the present study, and this might have contributed to the reduced milk secretion (Allen, 1990). The cessation of milking, causing increased intramammary pressure, may have reduced the activity of key mammary enzymes and thus reduced the metabolic capacity and production of milk lactose (Farr et al., 2000). An increased permeability of tight junctions of the mammary epithelium, causing paracellular leakage of lactose to blood plasma, may have contributed to the decreased lactose concentration in milk (Stelwagen et al., 1994). Reduction of feed also influences lactose secretion, and complete feed withdrawal results in a pronounced drop in lactose secretion in ruminants (Chaiyabutr et al., 1980; Agenäs et al., 2003). On the other hand, a 50% restriction of feed intake in late lactation induced a nonsignificant reduction in lactose secretion (Lacy-Hulbert et al., 1999). In the present study, the feed restriction imposed by the DO procedure was considered to be modest because the cows were fed 4 kg of DM as silage as well as straw ad libitum. It is therefore reasonable to assume that the effects of feed restriction on lactose output were limited. Thus, the observed reduction in lactose output was probably caused mainly by increased intramammary pressure because of prolonged milking intervals. However, other explanations are also possible.
The BHBA concentration was generally higher in HY and MY cows than in LY cows but dropped in all cows during DO, in agreement with Odensten et al. (2005a). It is probable that the drop mainly reflected a reduction in rumen absorption and epithelial oxidation of butyrate, and not the rate of liver ketogenesis (Aiello et al., 1984). The plasma urea concentration decreased during DO in all cows. We previously showed that rumen ammonia dropped markedly, concomitant with a drop in plasma urea, during DO (Odensten et al., 2005a). It is reasonable to assume that the reduction in plasma urea concentration reflects a decreased N intake.
In spite of a generally slightly higher milk production in the SH breed, there were no breed differences in milk yield at DO in our study. It is probable that the number of animals was too small to detect differences between breeds. Moreover, no interactions between breed and days relative to DO were found in any of the measured milk and plasma parameters, suggesting that the breeds responded equally to the DO procedure. As expected, SRB cows had a higher fat content in milk than did SH cows (Swedish Dairy Association, 2005). They also tended to have higher plasma concentrations of BHBA than did SH cows. A relation between milk fat and ketone bodies has been reported previously (Miettinen and Sätelä, 1993). Ketosis is also more common in SRB cows than in SH cows (Emanuelson et al., 1993).
There was no effect of calving interval on milk yield or composition. Plasma glucose was significantly higher and insulin tended to be higher in CI-15 cows than in CI-12 cows. This probably reflects a more positive energy balance among the CI-15 cows than the CI-12 cows. The CI-15 cows also had higher BCS at DO. In line with Österman et al. (2005), the cows in the CI-15 group in the present study did not have higher SCC prior to DO compared with the CI-12 cows.
In agreement with previous studies (Emanuelson et al., 1988; Odensten et al., 2007), the SCC, at both the cow and quarter levels, was significantly elevated during DO as compared with late lactation. This was especially true in low-yielding cows. In cows with good udder health, the elevated SCC at DO is mainly due to a concentration effect as the milk production decreases and to cell migration during involution of the mammary gland. However, there is also an increased risk of IMI during DO that gives rise to an increase in SCC. In line with other studies (Dingwell et al., 2004; Rajala-Schultz et al., 2005), IMI was less common immediately following calving in cows producing a lower milk yield at DO. This may have been due to the less common finding of open teat canals after DO in this group compared with the higher yielding groups. In the present study, which included a relatively small number of animals and quarters, we did not find a significant relationship between teat canal closure and IMI at calving. However, such an association was reported by Dingwell et al. (2004) using a much larger population. In another study, cows with milk leakage after DO as a result of incomplete teat canal closure were 4-fold more likely to develop clinical mastitis (Schukken et al., 1993). Teat-end condition has also been associated with IMI (Neijenhuis et al., 2001), but in the present study, teat condition did not differ between yield groups after DO. In the present study, the yield before DO did not significantly influence the SCC during the first 4 wk after parturition or the presence of IMI 4 wk after parturition, indicating a limited long-term influence on udder health. An effect of breed (lower SCC in SRB than in SH) was obvious before and during DO, as well as after parturition. This is consistent with a lower incidence of subclinical mastitis in SRB cows than in SH cows (Emanuelson et al., 1993; Swedish Dairy Association, 2005).
|
CONCLUSIONS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
|---|
|
ACKNOWLEDGEMENTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
|---|
Received for publication December 29, 2005. Accepted for publication October 27, 2006.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
|---|
This article has been cited by other articles:
|
|
 |
|
  C. B. Tucker, S. J. Lacy-Hulbert, and J. R. Webster Effect of milking frequency and feeding level before and after dry off on dairy cattle behavior and udder characteristics J Dairy Sci, July 1, 2009; 92(7): 3194 - 3203. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. A. van Dorland, S. Richter, I. Morel, M. G. Doherr, N. Castro, and R. M. Bruckmaier Variation in hepatic regulation of metabolism during the dry period and in early lactation in dairy cows J Dairy Sci, May 1, 2009; 92(5): 1924 - 1940. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A.-K. Nyman, U. Emanuelson, K. Holtenius, K. L. Ingvartsen, T. Larsen, and K. P. Waller Metabolites and Immune Variables Associated with Somatic Cell Counts of Primiparous Dairy Cows J Dairy Sci, August 1, 2008; 91(8): 2996 - 3009. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
, 5.0 to 11.4 kg of milk/d), medium (MY;
, 11.5 to 17.7 kg of milk/d), and high (HY; 
, 17.8 to 29.5 kg of milk/d). Values that differ (P < 0.05) from the control value before DO (mean from 2 samples) within treatment are indicated with filled symbols.
