首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 0 毫秒
1.
    
The objective of this study is to quantify the milk production response per cow and per hectare (ha) for an incremental stocking rate (SR) change, based on a meta-analysis of published research papers. Suitable experiments for inclusion in the database required a comparison of at least two SRs under the same experimental conditions in addition to details on experimental length and milk production results per cow and per ha. Each additional increased SR treatment was also described in terms of the relative milk production change per cow and per ha compared to the lower base SR (b_SR). A database containing 109 experiments of various lengths with 131 comparisons of SR was sub-divided into Type I experiments (common experimental lengths) and Type II experiments (variable experimental lengths). Actual and proportional changes in milk production according to SR change were analysed using linear mixed model procedures with study included as a random effect in the model. Low residual standard errors indicated a good precision of the predictive equations with the exception of proportional change in milk production per cow. For all milk yield variables analysed, the results illustrate that while production per cow is reduced, a strong positive relationship exists between SR and milk production per ha. An SR increase of one cow/ha resulted in a decrease in daily milk yield per cow of 7.4% and 8.7% for Type I and Type II data, respectively, whereas milk yield per ha increased by 20.1% and 19.6%, respectively. Within the Type II data set, a one cow/ha increase in SR also resulted in a 15.1% reduction in lactation length (equivalent to 42 days). The low predictability of proportional change in milk production per cow according to the classical SR definition of cows per ha over a defined period suggests that SR may be more appropriately defined in terms of the change in available feed offered per animal within each treatment.  相似文献   

2.
This study aimed at comparing the effects of once-a-day (OAD) milking during the descending phase of lactation between cows from the two most common breeds in France (Holstein and Montbéliarde). This study was carried on during two successive summers on a total of 50 Holstein and 38 Montbéliarde cows. During 7 weeks, half of the cows from each breed was milked OAD while the other half was milked twice a day (TAD). The animals were also followed for the next 3 or 5 weeks when they were all milked TAD, to check for any residual effect of OAD milking. The behaviour of OAD cows was observed around milking time. The incidence of diseases, the main performance variables (milk production, milk flow rate, live weight and body condition score), the detailed composition of milk (fat, protein, lactose, somatic cells, minerals, pH, free fatty acid (FFA), nitrogen fractions and enzymes) and some technological variables (clotting time and curd firmness) were measured on all cows.Some signs of disturbance were observed in the OAD cows at the time when milking was omitted: some cows mooed, some went close to the exit of the paddock, some leaked milk prior to milking. However, these signs disappeared after 2 days. After the experimental period, the live weight and the body condition score of TAD and OAD cows did not differ significantly. OAD cows produced 4.5 kg/day less than TAD (P < 0.001), this being more marked in Holstein (5.7 kg/day, P < 0.001) than Montbéliarde (3.3 kg/day, P < 0.001) cows. The milk contents of fat, whey protein, casein, total protein and phosphorus, and its plasminogen activity, were higher with OAD cows while lactose and FFA contents, and lipoprotein lipase activity were lower, with no interaction observed with breed. During the subsequent 3 weeks, when all cows were again milked TAD, OAD cows still produced 1.7 kg/day less milk (P < 0.01) with slightly higher fat and protein content.OAD milking for 7 weeks during the descending phase of lactation decreased milk production but increased milk content of most components, with a low residual effect. Montbéliarde cows were less affected by OAD milking than Holstein cows.  相似文献   

3.
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.  相似文献   

4.
    
The competitiveness and sustainability of low input cost dairy production systems are generally supported by efficient use of pasture in the diets. Therefore, pasture intake directly affects overall efficiency of these systems. We aimed to assess feeding and grazing management main factors that affect pasture dry matter intake (DMI) in commercial dairy farms during the different seasons of the year. Fortnightly visits to 28 commercial dairies were carried out between June 2016 and May 2017 to record production and price, supplement offered and price, pasture access time (PAT), herbage mass (HM) and allowance (HA). Only farms with the most contrasting estimated pasture DMI per cow (eDMI) were compared as systems with high (HPI; N = 8) or low (LPI; N = 8) pasture DMI. Despite a lower individual milk production in HPI than LPI (19.0 v. 23.3 ± 0.7 l/cow, P < 0.01), daily margin over feeding cost was not different between groups (3.07 v. 2.93 ± 0.15 U$S/cow for HPI and LPI, respectively). During autumn and winter, HPI cows ingested more pasture than LPI cows (8.3 v. 4.6 and 5.9 v. 2.9 ± 0.55 kg DM/cow per day, respectively, P < 0.01) although PAT, HM and HA were similar between groups. Both groups offered high supplementation levels during these seasons, even though greater in LPI than HPI (14.7 v. 9.7 ± 0.7 kg DM supplement/cow per day, respectively, P < 0.01). On the other hand, differences between groups for both pasture and supplement DMI were more contrasting during spring and summer (13.1 v. 7.3 ± 0.5 and 4.0 v. 11.4 ± 0.4 kg DM/cow per day for HPI and LPI, respectively, P < 0.01), with higher PAT in both seasons (P < 0.05) and higher HA during summer in HPI than LPI (P < 0.01). Unlike LPI, during these seasons HPI adjusted offered supplement according to HA, achieving a higher pasture eDMI and making more efficient use of available pastoral resource than LPI. As there was no grazing limiting condition for pasture harvesting in either group, the main factor affecting pasture DMI was a pasture by supplement substitution effect. These results reinforce the importance of an efficient grazing management, and using supplements to nutritionally complement pasture intake rather than as a direct way to increase milk production.  相似文献   

5.
    
Increased economic, societal and environmental challenges facing agriculture are leading to a greater focus on effective way to combine grazing and automatic milking systems (AMS). One of the fundamental aspects of robotic milking is cows’ traffic to the AMS. Numerous studies have identified feed provided, either as fresh grass or concentrate supplement, as the main incentive for cows to return to the robot. The aim of this study was to determine the effect of concentrate allocation on voluntary cow traffic from pasture to the robot during the grazing period, to highlight the interactions between grazed pasture and concentrate allocation in terms of substitution rate and the subsequent effect on average milk yield and composition. Thus, 29 grazing cows, milked by a mobile robot, were monitored for the grazing period (4 months). They were assigned to two groups: a low concentrate (LC) group (15 cows) and a high concentrate (HC) group (14 cows) receiving 2 and 4 kg concentrate/cow per day, respectively; two allocations per day of fresh pasture were provided at 0700 and 1600 h. The cows had to go through the AMS to receive the fresh pasture allocation. The effect of concentrate level on robot visitation was calculated by summing milkings, refusals and failed milkings/cow per day. The impact on average daily milk yield and composition was also determined. The interaction between lactation number and month was used as an indicator of pasture availability. Concentrate allocation increased significantly robot visitations in HC (3.60±0.07 visitations/cow per day in HC and 3.10±0.07 visitations/cow per day in LC; P<0.001) while milkings/cow per day were similar in both groups (LC: 2.37±0.02/day and HC: 2.39±0.02/day; Ns). The average daily milk yield over the grazing period was enhanced in HC (22.39±0.22 kg/cow per day in HC and 21.33±0.22 kg/cow per day in LC; P<0.001). However the gain in milk due to higher concentrate supply was limited with regards to the amount of provided concentrates. Milking frequency in HC primiparous compared with LC was increased. In the context of this study, considering high concentrate levels as an incentive for robot visitation might be questioned, as it had no impact on milking frequency and limited impact on average milk yield and composition. By contrast, increased concentrate supply could be targeted specifically to primiparous cows.  相似文献   

6.
    
The aim of this paper was to study the relationship between milk flow emission variables recorded during milking of dairy goats with variables related to milking routine, goat physiology, milking parameters and milking machine characteristics, to determine the variables affecting milking performance and help the goat industry pinpoint farm and milking practices that improve milking performance. In total, 19 farms were visited once during the evening milking. Milking parameters (vacuum level (VL), pulsation ratio and pulsation rate, vacuum drop), milk emission flow variables (milking time, milk yield, maximum milk flow (MMF), average milk flow (AVMF), time until 500 g/min milk flow is established (TS500)), doe characteristics of 8 to 10 goats/farm (breed, days in milk and parity), milking practices (overmilking, overstripping, pre-lag time) and milking machine characteristics (line height, presence of claw) were recorded on every farm. The relationships between recorded variables and farm were analysed by a one-way ANOVA analysis. The relationships of milk yield, MMF, milking time and TS500 with goat physiology, milking routine, milking parameters and milking machine design were analysed using a linear mixed model, considering the farm as the random effect. Farm was significant (P<0.05) in all the studied variables. Milk emission flow variables were similar to those recommended in scientific studies. Milking parameters were adequate in most of the farms, being similar to those recommended in scientific studies. Few milking parameters and milking machine characteristics affected the tested variables: average vacuum level only showed tendency on MMF, and milk pipeline height on TS500. Milk yield (MY) was mainly affected by parity, as the interaction of days in milk with parity was also significant. Milking time was mainly affected by milk yield and breed. Also significant were parity, the interaction of days in milk with parity and overstripping, whereas overmilking showed a slight tendency. We concluded that most of the studied variables were mainly related to goat physiology characteristics, as the effects of milking parameters and milking machine characteristics were scarce.  相似文献   

7.
    
Because not all animal factors influencing profitability can be included in total merit breeding indices for profitability, the association between animal total merit index and true profitability, taking cognisance of all factors associated with costs and revenues, is generally not known. One method to estimate such associations is at the herd level, associating herd average genetic merit with herd profitability. The objective of this study was to primarily relate herd average genetic merit for a range of traits, including the Irish total merit index, with indicators of performance, including profitability, using correlation and multiple regression analyses. Physical, genetic and financial performance data from 1131 Irish seasonal calving pasture-based dairy farms were available following edits; data on some herds were available for more than 1 year of the 3-year study period (2007 to 2009). Herd average economic breeding index (EBI) was associated with reduced herd average phenotypic milk yield but with greater milk composition, resulting in higher milk prices. Moderate positive correlations (0.26 to 0.61) existed between genetic merit for an individual trait and average herd performance for that trait (e.g. genetic merit for milk yield and average per cow milk yield). Following adjustment for year, stocking rate, herd size and quantity of purchased feed in the multiple regression analysis, average herd EBI was positively and linearly associated with net margin per cow and per litre as well as gross revenue output per cow and per litre. The change in net margin per cow per unit change in the total merit index was €1.94 (s.e. = 0.42), which was not different from the expectation of €2. This study, based on a large data set of commercial herds with accurate information on profitability and genetic merit, confirms that, after accounting for confounding factors, the change in herd profitability per unit change in herd genetic merit for the total merit index is within expectations.  相似文献   

8.
    
The time constraints of the classic twice-daily milking routine are less easily endured by individual dairy farmers, because of their impact on quality of life. Our aim was to evaluate milk production responses by dairy cows milked twice daily at contrasting intervals. In experiments 1 (20 cows) and 2 (28 cows), four milking regimes were compared during a 3-week period beginning after the peak of lactation. Three groups of five cows were milked twice daily (TDM) with milking intervals of 11 : 13, 7 : 17 and 3 : 21 h in experiment 1, and three groups of seven cows at 11 : 13, 5 : 19 and 2.5 : 21.5 h in experiment 2. One group (five and seven cows respectively) was milked once daily (ODM) in each experiment. In experiment 3 (three groups, 12 cows per group), one group was milked at 10 : 14 h and one at 5 : 19 h, and the third group once daily. Milking treatments began during the second week of lactation and continued for an average of 23 weeks. In experiments 1 and 2, daily milk yields were reduced by 4.1%, 11.5% and 28%, for the 5 : 19, 3 : 21 and ODM milking treatments compared with the 11 : 13 h interval. In experiment 3, the decrease in daily milk yields for 5 : 19 h and ODM was 10% and 40% compared with the 10 : 14 h time interval. In the average daily milk, fat and protein contents and somatic cell counts were not different between the TDM groups, and the ODM group had (or tended to have) a higher fat and protein content. For a given milking, milk fat content decreased from about 60 to 32 g/kg as the preceding milking interval increased from 2.5 to 3 h up to 12 h. It then levelled out and even increased, mainly after 18 to 20 h. Somatic cell count showed a similar trend, and protein content did not change steadily. Dry matter intake, body weight and body condition score were not affected by contrasting milking intervals. After resumption of TDM with conventional intervals, productions of milk, fat and protein no longer differed between the TDM groups. Milk yield of previously ODM cows remained lower by 2 kg/day (P = 0.15) in experiments 1 and 2, and by 7 kg/day (P < 0.05) in experiment 3. These results suggest that TDM at contrasting intervals up to 5 : 19 h is feasible as it decreases milk yield only moderately, especially if implemented from peak of lactation.  相似文献   

9.
    
Diets combining herbage and total mixed rations (TMR) are increasingly used in temperate regions for feeding ruminants, but little information is available regarding the effects on nutrient intake and digestion of this feeding management in beef cattle. The aim of this study was to determine the effects of combining TMR (10% CP and 13% ADF), and legume-based herbage (14% CP and 27% ADF) on intake, nutrient digestion, ruminal fermentation, microbial N flow and glucose and nitrogen metabolism in heifers. The experiment was a 3×3 Latin square design replicated three times; each period lasted 18 days (10 adaptation days and 8 measurement days). Nine cross-bred (Aberdeen Angus×Hereford) heifers (214±18 kg) fitted with permanent rumen catheters and housed in individual metabolic cages were assigned to one of three treatments: 24 h access to TMR (T), 24 h access to herbage (H) or combined diets with 18 h access to TMR and 6 h access to herbage (T+H). Data were evaluated using a mixed model. Animals fed T+H (TMR 71% and herbage 29%) diets tended to have a higher dry matter intake as a proportion of their BW than animals fed T. The T+H diet did not change ruminal fermentation (pH, N–NH3 and volatile fatty acids) or the N metabolism relative to the T diet, but increased the glucagon concentration and altered glucose metabolism. Conversely, animals fed T+H had increased purine derivatives excretion, increased N use efficiency for microbial protein synthesis and decreased plasma urea and urinary N excretion relative to animals fed H diet. The use of combined diets led to consumption of nutrients similar to a TMR diet, without reducing nutrient use and could improve N utilization compared with the herbage-only diet.  相似文献   

10.
    
Early detection of post-calving health problems is critical for dairy operations. Separating sick cows from the herd is important, especially in robotic-milking dairy farms, where searching for a sick cow can disturb the other cows’ routine. The objectives of this study were to develop and apply a behaviour- and performance-based health-detection model to post-calving cows in a robotic-milking dairy farm, with the aim of detecting sick cows based on available commercial sensors. The study was conducted in an Israeli robotic-milking dairy farm with 250 Israeli-Holstein cows. All cows were equipped with rumination- and neck-activity sensors. Milk yield, visits to the milking robot and BW were recorded in the milking robot. A decision-tree model was developed on a calibration data set (historical data of the 10 months before the study) and was validated on the new data set. The decision model generated a probability of being sick for each cow. The model was applied once a week just before the veterinarian performed the weekly routine post-calving health check. The veterinarian’s diagnosis served as a binary reference for the model (healthy–sick). The overall accuracy of the model was 78%, with a specificity of 87% and a sensitivity of 69%, suggesting its practical value.  相似文献   

11.
    
The effect of supplementing high-quality fresh forage, mainly based on alfalfa, to growing lambs fed with decreasing levels of total mixed ration (TMR) was studied on intake, digestion and ruminal environment. In total, 24 catheterized lambs (25.2±3.67 kg) housed in individual metabolism cages were assigned to one of four treatment diets: ‘TMR100’: TMR offered ad libitum; ‘TMR75’ and ‘TMR50’: TMR at a level of 0.75 and 0.50 of potential intake, respectively, complemented with fresh forage without restriction; ‘TMR0’: only fresh forage ad libitum. The feeding behavior, nutrient intake and digestibility, kinetics of passage and rumen environment were evaluated. As the level of TMR in the diet decreased, lambs increased the forage intake and spent more time eating and ruminating, less time resting and demonstrated a higher rate of intake. Those changes resulted in a higher nutrient intake of dry matter, organic matter, nitrogen, NDF and ADF, but a slightly lower organic matter digestibility, while no differences were detected in the output rate of particles. As a consequence, with the decrease of TMR and increase of forage intake, the ingested energy increased. Higher ruminal pH and NH3–N concentrations were observed for lower levels of TMR in the diet. The total volatile fatty acids, acetate and propionate concentrations presented a quadratic response. Total volatile fatty acids and acetate concentrations were higher and propionate concentration was lower in lambs consuming mixed diets (TMR50 and TMR75). We concluded that the inclusion of high-quality fresh forage in a combined diet with TMR in lambs had positive effects on nutrient intake without negative consequences on digestion and rumen environment.  相似文献   

12.
    
The milking ability of Lacaune ewes was characterised by derived traits of milk flow patterns, in an INRA experimental farm, from a divergent selection experiment in order to estimate the correlated effects of selection for protein and fat yields. The analysis of selected divergent line effects (involving 34 616 data and 1204 ewes) indicated an indirect improvement of milking traits (+17% for maximum milk flow and -10% for latency time) with a 25% increase in milk yield. Genetic parameters were estimated by multi-trait analysis with an animal model, on 751 primiparous ewes. The heritabilities of the traits expressed on an annual basis were high, especially for maximum flow (0.54) and for latency time (0.55). The heritabilities were intermediate for average flow (0.30), time at maximum flow (0.42) and phase of increasing flow (0.43), and low for the phase of decreasing flow (0.16) and the plateau of high flow (0.07). When considering test-day data, the heritabilities of maximum flow and latency time remained intermediate and stable throughout the lactation. Genetic correlations between milk yield and milking traits were all favourable, but latency time was less milk yield dependent (-0.22) than maximum flow (+0.46). It is concluded that the current dairy ewe selection based on milk solid yield is not antagonistic to milking ability.  相似文献   

13.
    
Behavioural and cardiac responses of multiparous dairy cows (n=24) during milking in a 2×4 stall herringbone milking system were evaluated in this study. Heart rate (HR), parasympathetic tone index (high frequency component, HF) of heart rate variability and sympathovagal balance indicator LF/HF ratio (the ratio of the low frequency (LF) and the HF component) were analysed. Measurement periods were established as follows: (1) standing calm (baseline), (2) udder preparation, (3) milking, (4) waiting after milking in the milking stall and (5) in the night (2 h after milking). Step behaviour was recorded and calculated per minute for the three phases of the milking process (udder preparation, milking and waiting after milking). HR was higher during udder preparation and milking compared with baseline (P=0.03, 0.027, respectively). HF was significantly lower than baseline levels during waiting in the milking stall after milking (P=0.009), however, during udder preparation, milking and 2 h after milking did not differ from baseline (P>0.05, in either case). LF/HF during the three phases of the milking process differed neither from baseline levels nor from each other. Steps occurred more often during waiting after milking than during udder preparation (P=0.042) or during milking (23; P=0.017). Our results suggest that the milking procedure itself was not stressful for these animals. After milking (following the removal of the last teat cup and before leaving the milking stall), both decreased parasympathetic tone (lower HF) and increased stepping rate indicated a sensitive period for animals during this phase.  相似文献   

14.
    
Mastitis is one of the most prevalent and costly diseases in dairy cattle. Key components for adequate mastitis control are the detection of early stages of infection, as well as the selection of appropriate management interventions and therapies based on the causal pathogens associated with the infection. The objective was to characterize the pattern of electrical conductivity (EC) in milk during intramammary infection, considering specific mastitis-causing pathogen groups involvement. Cows (n = 200) identified by an in-line mastitis detection system with a positive deviation ≥15% in the manufacturer’s proprietary algorithm for EC (high electrical conductivity (HEC)) were considered cases and enrolled in the study at the subsequent milking. One control (CON) cow, within normal ranges for EC, was matched to each case. A composite milk sample was collected aseptically from each cow for bacteriological culture. Milk yield (MY) and EC were recorded for each milking during ±7 days relative to enrollment. Milk cultures were categorized into gram positive (GP), gram negative (GN), other (OTH) and no growth (NOG). Data were submitted for repeated-measures analysis with EC as the dependent variable and EC status at day −1, bacteriological culture category, parity number, stage of lactation and days relative to sampling as main independent variables. Average (± standard error (SE)) EC was greater in HEC than in CON cows (12.5 ± 0.5 v. 10.8 ± 0.5 mS/cm) on the day of identification (day −1). Milk yield on day −1 was greater in CON than in HEC (37.6 ± 5.1 v. 33.5 ± 5.2 kg). For practical management purposes, average EC on day −1 was similar for the different bacteriological culture categories: 11.4 ± 0.6, 11.7 ± 0.5, 12.3 ± 0.8 and 11.7 ± 0.5 mS/cm in GN, GP, OTH and NOG, respectively. Parity number was only associated with day −1 EC in HEC group, with the greatest EC values in parity 3 (12.3 ± 0.3 mS/cm), followed by parity 2 (11.9 ± 0.2 mS/cm), parity >3 (11.6 ± 0.5 mS/cm) and primiparous cows (11.2 ± 0.2 mS/cm). An effect on EC for the interaction of day relative to identification by pathogen gram category was observed. The same interaction effect was observed on daily MY. Overall, the level of variation for MY and EC between- and within-cows was substantial, and as indicated by the model diagnostic procedures, the magnitude of the variance in the cows in the CON group resulted in deviations from normality in the residuals. We concluded that characteristic temporal patterns in EC and MY in particular pathogen groups may provide indications for differentiation of groups of mastitis-causing pathogens. Further research to build detection models including EC, MY and cow-level factors is required for accurate differentiation.  相似文献   

15.
    
Cow routines and behavioral responses are altered substantially following the installation of robot milking. The present study was designed to analyze the effect that switching from milking parlor to automatic milking system (AMS) had on the culling rate (due to various causes) of dairy cattle. For this purpose, culling records and causes for culling were tracked in 23 dairy farms in the Galicia region (NW Spain). The animals in these farms were monitored for 5 years. For the present study, that length of time was divided into three different stages, as follows: 2 years before switching from a milking parlor to AMS (stage 1), the 1st year following the implementation of AMS (stage 2) and the 2nd and 3rd years succeeding the implementation of AMS (stage 3). Cox models for survival analysis were used to estimate the time to culling due to different reasons during stage 1 in relation to stages 2 and 3. The data indicated that the risk of loss due to death or emergency slaughter decreased significantly following the installation of AMS. In contrast, the risk of culling due to low production, udder problems, infertility or lameness increased significantly. Low-production cows (such as cows in advanced lactation due to infertility) or sick cows (such as mastitic or lame cows) allegedly have a noticeable effect both on the performance and the amortization of the cost of AMS, which in turn would lead to a higher probability of elimination than in conventional systems.  相似文献   

16.
    
Genetic selection for milking speed is feasible. The existence of a correlation structure between milking speed and milk yield, however, necessitates a selection strategy to increase milking speed with no repercussion on genetic merit for milk yield. Residual milking duration (RMD) and residual milking duration including somatic cell score (RMDS), defined as the residuals from a regression model of milking duration on milk yield or milk yield plus somatic cell score (SCS) have been advocated. The objective of this study was to undertake a first ever genetic analysis of these novel traits. Data on electronically recorded milking duration and other milking characteristics from 235 005 test-day records on 74 608 cows in 1075 Irish dairy herds were available. Variance components for the milking characteristic traits were estimated using animal linear mixed models and covariances with other performance traits, including udder-related type traits, were estimated using sire models. The heritability of milking duration, RMD and RMDS was 0.20, 0.22 and 0.18, respectively. There were little differences in the heritability of RMD or RMDS when defined using genetic regression. The genetic standard deviation of RMDS defined on the phenotypic or genetic level was 36.8 s and 37.6 s, respectively, clearly indicating considerable exploitable genetic variation in milking duration independent of both milk yield and SCS. The genetic correlation between phenotypically derived RMDS and milk yield was favourable (−0.43), but RMDS was unfavourably genetically correlated with SCS (−0.30); the genetic correlations with both traits when RMDS was defined at a genetic level were zero. RMDS defined at the phenotypic level was negatively (i.e. unfavourable) genetically correlated (−0.35; s.e. = 0.15) with mastitis; however, when defined using genetic regression, shorter RMDS was not associated with greater expected incidence of mastitis. RMDS, defined at the genetic level, is a useful heritable trait with ample genetic variation for inclusion in a national breeding strategy without influencing genetic gain in either milk yield or udder health.  相似文献   

17.
    
This study investigates the effects of two feeding systems and two dairy cow breeds on milk yield and composition, physical and sensorial properties of Camembert and Pont-l’Evêque cheeses. The experiment consisted of a 2 × 2 factorial arrangement of treatments. A low energy grass diet with only 15% of concentrate (LowGS) was compared with a high-energy maize silage diet with 30% concentrate (HighMS). Thirty-four Holstein (Ho) and 34 Normande (No) cows in early lactation were assigned to one of two feeding systems for a 6-week period. Cows on the LowGS feeding system had lower milk yield, fat and protein content. In both feeding systems, No cows had lower milk yields but higher milk protein contents than Ho cows. The LowGS feeding system altered milk fatty acid (FA) composition by reducing saturated FA. Breed had only a small impact on milk FA. Concerning milk coagulating properties, only the firmness was reduced by the LowGS feeding and the Ho breed. The effects of breed and feeding system on the protein content of cheeses were more marked in Camembert cheese than in Pont-l’Evêque cheese. However, the Camembert cheese from Ho-LowGS was, in fact, characterized especially by lower protein content. LowGS feeding system and No breed produced more yellow cheeses. Feeding systems had limited effects on the firmness of Camembert and Pont-l’Evêque cheeses measured by penetrometry. In sensory analysis, Ho breed and LowGS feeding produced a Camembert cheese with a more melting texture in the mouth due to the increase of spreadability index and of proteolysis. The type of cheese also had an influence: the effects were more important on Camembert cheese than on Pont-l’Evêque cheese. Only the Ho-LowGS treatment produced a very specific Camembert cheese different from the others. The feeding systems and breed of dairy cow have no determinant effect on PDO (protected designation of origin) Camembert and Pont-l’Evêque cheeses, especially regarding taste. In this kind of trial, despite the effects of feeding systems and breed on milk composition, the role of cheese ripening and microbiology appears to be of considerable importance.  相似文献   

18.
    
The objective of this field study with an automatic milking system was to evaluate the effects of omitting the dry period on health and productivity during the subsequent lactation in dairy cows. A total of 98 German Simmental cows of six Southern German farms were assigned randomly to two experimental groups: The first group was dried-off 56 days before calving (D for dried-off, n=49), and the second group was milked continuously during this period until calving (CM for continuous milking, n=49). From the latter a third group emerged, including cows that dried-off themselves spontaneously (DS for dried-off spontaneously, n=14). Blood serum values of glucose, β-hydroxybutyrate (BHBA), non-esterified fatty acids (NEFA) and IGF-1 showed most pronounced fluctuations in D cows. Over the entire study period, the concentrations of BHBA and NEFA were markedly lower in the CM and DS groups. Furthermore, IGF-1 concentration was lowest for D cows and also decrease in back fat thickness was more pronounced. Mean concentration of milk protein was markedly higher in CM and DS cows (3.70% and 3.71%) compared with D cows (3.38%). Owing to the lower 305-day milk yield (−15.6%) and the lower total milk yield (−3.1%), the total amount of produced protein in the subsequent lactation was 2.5% (6.8 kg) lower, although the additional protein amount in CM cows from week −8 to calving was 35.7 kg. The greatest benefit resulted from positive effects on fertility and the lower incidence of diseases: CM cows had their first oestrus 1 week earlier compared with D cows, they also conceived earlier and showed a significantly lower risk of developing hypocalcaemia, ketosis and puerperal disorders. The present study showed that the costs of medical treatment and milk losses were twice as high in D cows, compared with CM and DS cows, and thus the reduced costs because of the more stable health outweighed the financial losses of milk yield by +18.49 € per cow and lactation.  相似文献   

19.
    
Animal health issues are a problem on many dairy farms, and much is already known about clinical treatments and the behaviour of sick animals. Animal health issues can influence behaviour seen around the milking parlour, but less is known about the relationship between the number of previous medical treatments and the queuing to be milked, the ‘milking order’. Information was collected on five afternoon milking sessions, the individual cows’ age and the medical treatment history of each cow in a group of 100 cows. The question addressed was whether the age and the medical treatment history of each cow in the herd affected its milking order. In addition, milking order was tested day to day, and was found to be consistent. A significant positive correlation was found between medical treatment history and milking order rank, meaning that cows with a higher medical treatment history tended to enter the milking parlour later than cows with a lower medical treatment history. In contrast with this finding, it was found that older cows were more likely to enter the milking parlour early when compared to younger animals, a finding which is supported by previous studies. These somewhat contradictory effects of (a) age and (b) medical treatment history on milking order suggest that health disorders may have long-term measurable effects on the position of a cow in the milking order, even when the effect of age on milking order is accounted for.  相似文献   

20.
The aim of this study was to evaluate the effects on dairy performance and milk fatty acid (FA) composition of (i) supplementation with extruded linseed (EL), (ii) supplementation with synthetic or natural antioxidants, namely vitamin E and plant extracts rich in polyphenols (PERP), (iii) cow breed (Holstein v. Montbéliarde) and (iv) time of milking (morning v. evening). After a 3-week pre-experimental period 24 lactating cows (12 Holstein and 12 Montbéliarde) were divided up into four groups of six cows: the first group received a daily control diet (diet C) based on maize silage. The second group received the same diet supplemented with EL (diet EL, fat level approximately 5% of dietary dry matter (DM)). The third group received the EL diet plus 375 IU/kg diet DM of vitamin E (diet ELE). The fourth group received the ELE diet plus 10 g/kg diet DM of a PERP mixture (diet ELEP). Compared with the diet C, feeding EL-rich diets led to lower concentrations of total saturated FA (SFA) and higher concentrations of stearic and oleic acids, each trans and cis isomer of 18:1 (except c12-18:1), non-conjugated isomers of 18:2, some isomers (c9t11-, c9c11- and t11t13-) of conjugated linoleic acid (CLA), and 18:3n-3. The vitamin E supplementation had no effect on milk yield, milk fat or protein percentage and only moderate effects on milk concentrations of FA (increase in 16:0, decreases in 18:0 and t6/7/8-18:1). The addition of PERP to vitamin E did not modify milk yield or composition and slightly altered milk FA composition (decrease in total saturated FA (SFA) and increase in monounsaturated FA (MUFA)). The minor effects of vitamin E may be partly linked to the fact that no milk fat depression occurred with the EL diet. During both periods the Holstein cows had higher milk production, milk fat and protein yields, and milk percentages of 4:0 and 18:3n-3, and lower percentages of odd-branched chain FA (OBCFA) than the Montbéliarde cows. During the experimental period the Holstein cows had lower percentages of total cis 18:1, and c9,c11-CLA, and higher percentages of 6:0, 8:0, t12-, t16/c14- and t13/14-18:1, and 18:2n-6 than Montbéliarde cows because of several significant interactions between breed and diet. Also, the total SFA percentage was higher for morning than for evening milkings, whereas those of MUFA, total cis 18:1, OBCFA and 18:2n-6 were lower. Extruded linseed supplementation had higher effect on milk FA composition than antioxidants, breed or time of milking.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号