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1.
Missanjo EM Imbayarwo-Chikosi VE Halimani TE 《Tropical animal health and production》2011,43(3):665-667
A study was carried out to establish the factors affecting milk, butterfat and protein yields in Zimbabwean Jersey cattle.
A total of 10,986 unedited 305-day lactation records were obtained from Zimbabwe Livestock Identification Trust containing
25 herds, with cows calving in the period 1996–2008. The general linear model procedure of the Statistical Analysis Systems
version 9.1.3 was used to determine the environmental factors. Herd-year-season, calving interval, days dry and both the linear
and quadratic effects of age at calving fitted as covariates significantly (P < 0.0001) affected the milk, fat and protein yields. Herd-year-season accounted for 36%, 36% and 35% to the total variation
in milk, fat and protein yields, respectively. Milk, fat and protein yields increased with an increase in calving interval.
The optimum dry period for milk, fat and protein yields obtained was 60–75 days dry. The relationship between the production
traits and age at calving was both linear and quadratic, implying that milk, fat and protein yields increase with the age
of the animal. It is thus necessary to preadjust data for these environmental factors when carrying out genetic evaluations
of production traits in dairy cattle. 相似文献
2.
Seventy multiparous healthy lactating Holstein cows (fat-corrected milk yield = 7,561.8 kg) were monitored from 14 days before
to 70 days after calving. Transrectal ultrasound scanning was performed twice weekly from 7 to 65 days postpartum. Blood samples
were also collected twice weekly to measure serum P4 and biweekly to detect serum β-hydroxybutyrate (βHB) and nonesterified fatty acid (NEFA) concentrations. Body condition score
(BCS) was taken biweekly after calving. Based on the serum P4 profile of 59 cows (11 cows were excluded due to the occurrence of postpartum diseases) studied, 27 (45.8%) had normal ovarian
activity, while 21 (35.6%), six (10.1%), three (5.1%), and two (3.4%) had delayed ovulation (DOV), prolonged luteal phase
(PLP), short luteal phase (SLP), and cessation of ovarian activity, respectively. Cows with PLP had an earlier ovulation compared
to that of cows with normal ovarian activity (23.16 ± 4.02 vs 31.9 ± 8.35 days; P < 0.05). PLP cows also had a greater mean ± standard deviation peak milk yield (44.2 ± 5.8 vs 37.2 ± 5.7 kg/day, 75 days
postpartum; P < 0.05) than cows with normal postpartum ovarian activity. The PLP group also had greater milk production in the previous
lactation period. Logistic regression analysis indicated that cows with P4 concentration ≥1 ng/ml on day 24 after calving were more at risk for PLP by 1.1 for each 1 kg increase in mean peak milk
yield during 75 days after calving. BCS was lower in cows with DOV compared to that of cows with normal ovarian activity at
any time after calving (P < 0.05). Serum βHB concentrations in DOV cows were significantly higher than that of normal cows on day 42 after calving
(0.69 ± 0.29 vs 0.54 ± 0.12 mmol/L, P < 0.05). No significant difference was found in the mean concentrations of NEFA between cows in different groups at any time
after calving (P > 0.05). The concentrations of P4 on days 28 and 31 were negatively correlated with βHB concentration on day 42 after calving in cows with normal ovarian activity
(R = −0.44, P = 0.02). In conclusion, these findings suggest that early ovulation and hence early postpartum P4 rise in addition to the high milk production could partly be responsible for the occurrence of PLP in dairy cows. 相似文献
3.
Reproductive performance of Holstein dairy cows in Iran 总被引:2,自引:2,他引:0
Maryam Ansari-Lari Mojtaba Kafi Mohammad Sokhtanlo Hasan Nategh Ahmadi 《Tropical animal health and production》2010,42(6):1277-1283
The objectives of the present study were to describe the current reproductive parameters of Holstein dairy cows in Iran and
to determine factors which have a significant effect on reproductive performance with emphasis on high-producing dairy cows.
Five large Holstein dairy herds from the major milk production areas of Iran were selected for this study. Reproduction data
including parity of dam, calving date, days to first service, days open, number of services, dry period, and occurrence of
diseases for cows that calved from 2004 to 2007 were collected from the herds' databases. To determine the effects of year
and season of calving, disease status, level of milk production, and parity of dam on reproductive parameters, the proc-mixed
procedure in SAS software was used. Overall, data about 8,204 lactation were collected for the study. Results showed that
mean (±SD) days open, calving interval, and days to first service for study herds were 134 (±89), 403 (±86), and 67 (±38)
days, respectively. Conception rates at the first service and the overall service-conception rate were 41.6% and 41%, respectively.
The level of milk production and diseases had significant negative effects on days open and service per conception (P < 0.05); statistical analysis showed that for every 100-kg increase in milk yield, days open will increase by about 0.3 days.
However, no significant effect of level of productivity was observed on days to first service. The results of this study indicate
that high milk production is a risk factor for decreasing fertility in Iran, like many other parts of the world. 相似文献
4.
Amin Tamadon Mojtaba Kafi Mehdi Saeb Abdolah Mirzaei Saedeh Saeb 《Tropical animal health and production》2011,43(1):29-34
The relations between body condition score (BCS), milk yield, serum insulin-like growth factor-I (IGF-I) profile, and luteal
activity were investigated in postpartum dairy cows. Seventy-one healthy high-producing multiparous Holstein cows were subjected
to transrectal ultrasound scanning twice weekly from the first to the eighth week postpartum. Blood samples were collected
twice weekly to measure serum progesterone (P4) and every 2 weeks to detect serum IGF-I concentrations. BCS was monitored
weekly after calving. Cows with serum P4 concentrations ≥1 ng/ml on at least two consecutive samplings were considered to
have commenced luteal activity. Commencement of luteal activity (C-LA) was observed earlier than 45 days postpartum in 71.8%
of cows while 28.2% showed C-LA later than 45 days. Prolonged luteal phase was the most common abnormal pattern of luteal
activity observed. Cows with a C-LA earlier than 45 days postpartum had higher (P ≤ 0.05) mean serum concentrations of IGF-I than those with later C-LA. In addition, cows which showed C-LA earlier than 45 days
postpartum had more optimal productive indices including shorter calving to conception interval and calving to first service
interval (P ≤ 0.05), and fewer services per conception (P = 0.07). C-LA was significantly later in cows that lost more than 0.5 BCS units within 3 weeks postpartum than in those that
lost less than 0.5 units BCS during the same interval (P = 0.02). We conclude that high-producing dairy cows with higher postpartum serum IGF-I concentrations have earlier commencement
and normal luteal activity, and better reproductive performance. Severity and duration of BCS loss adversely affect commencement
of luteal activity. 相似文献
5.
A two-year longitudinal study was conducted to assess the reproductive and lactation performances of smallholder crossbred
dairy cattle in Fitche, central Ethiopia. Twenty-four smallholder dairy farms were monitored and data on reproductive, breeding,
lactation and management aspects of crossbred dairy cows (n = 69) were collected and analysed. Moreover, milk samples were collected and analysed for progesterone. The overall Least-squares
means for calving interval (CI), calving to conception interval (CCI) and first observed oestrus after calving were 516, 253
and 141 days, respectively. Suckling significantly prolonged these intervals. The mean first onset of luteal activity (OLA)
after calving was 52 days, while 67.4% (n = 43) had a delayed (>55 days) return to cyclicity after calving. Suckling and parity number significantly (p < 0.05) influenced the OLA. The mean lactation length was 54.4 weeks. The overall daily mean milk yield for the first 43 weeks
of lactation after calving was 11.7 L/day. The estimated daily milk yield increased slowly and reached peak (13.8 L/day) around
the 11th week post partum and declined gradually and steadily. Suckling status, season of calving and parity number significantly influenced the estimated
daily milk yield. In conclusion, the present study indicated that the smallholder crossbred dairy cows in the study area had
prolonged intervals to first oestrus after calving, to conception and to the next calving, and thus their reproductive performance
is unsatisfactory. Delayed first onset of luteal activity (postpartum anoestrus) contributed to these extended intervals.
Further detailed investigation is suggested to examine the effects of other relevant factors on the reproductive and lactation
performances of smallholder crossbred dairy cows for appropriate intervention. 相似文献
6.
The objective of this study was to evaluate the association between cow-specific risk factors and the lactational incidence
risks of retained placenta (RP), metritis (MET) and clinical mastitis (CM) in 57,301 dairy cows on 20 large dairy herds in
Iran between January 2005 and June 2009. A multivariable logistic regression model was used to identify risk factors for MET,
RP and CM and quantify their odds ratio (OR). The lactational incidences of MET, RP and CM were 8%, 5.2% and 18.9%, respectively,
and significant risk factors for MET were dystocia (OR = 4.32), stillbirth (OR = 6.26), RP (OR = 27.74), twin births (OR = 6.57),
primiparity (OR = 1.68), calving during winter season (OR = 2.45) and male calves (OR = 2.41). Significant risk factors for
RP were dystocia (OR = 3.17), stillbirth (OR = 3.18), abortion (OR = 8.46), milk fever (OR = 3.66), twin births (OR = 2.76),
pluriparity (OR = 2.69), calving during winter season (OR = 1.86) and shorter gestation length of dairy cows (OR = 3.82).
Also, significant risk factors for CM were RP (OR = 9.45), milk fever (OR = 12.36), pluriparity (OR = 2.83), calving during
winter season (OR = 1.68) and the first months of lactation (P < 0.001)) and SCC concentrations at previous lactation (OR = 1.82). The current study indicates that differentiation can
be made among cows in the risk of having MET, RP and CM based on a combination of cow factors. These differences among cows
could be useful to aid the better detection of these diseases in the dairy herds. 相似文献
7.
Fernández-Silva JA Abdulmawjood A Akineden O Bülte M 《Tropical animal health and production》2011,43(8):1501-1507
The objective of this study is the detection of Mycobacterium avium subsp. paratuberculosis (MAP) by serum enzyme-linked immunosorbent assay (ELISA), fecal polymerase chain reaction (PCR), and fecal culture in Colombian
dairy herds. Serum and fecal samples from asymptomatic cows (n = 307) of 14 dairy herds were tested for MAP by an unabsorbed ELISA test (ELISA-A). Serum and fecal samples from positive
ELISA-A animals (n = 31) were further tested by an absorbed ELISA test (ELISA-B) and PCR. Fecal samples from animals of herds positive by ELISA-A
and PCR (n = 105) were inoculated onto three different culture media. ELISA-A produced positive results in 10% of the serum samples
and 71% of the herds. ELISA-B and PCR results were positive in two and six serum and fecal samples from positive ELISA-A animals,
respectively. Fecal samples were negative for MAP on all culture media. The results of this study confirmed the presence of
MAP in local dairy herds and the difficulties of MAP detection in asymptomatic animals by ELISA, PCR, and fecal culture. 相似文献
8.
Dystocia in Friesian cows and its effects on postpartum reproductive performance and milk production
Gaafar H. M. A. Shamiah Sh. M. El-Hamd M. A. Abu Shitta A. A. El-Din M. A. Tag 《Tropical animal health and production》2011,43(1):229-234
A total of 1,243 records for 585 dairy Friesian cows from 1997–2004 were used to study the factors affecting dystocia and
its effects on reproductive performance and milk production. The overall incidence of dystocia was 6.9%. The percentage of
dystocia decreased with increasing live body weight, age, and parity of cows (P < 0.05); however, it increased with increasing birth weight of calves (P < 0.05). The highest percentage of dystocia was detected in winter season, but the least percentage was in summer season
(P < 0.05). The percentage of incidence of dystocia was significantly (P < 0.05) higher with winter feeding compared to summer ration (8.2% vs. 5.1%). The percentage of incidence of dystocia was
significantly (P < 0.05) higher with twinning than single calving (15.5% vs. 6.5%), while not significantly affected by the sex of born calves.
Incidence of dystocia had adverse effects on reproductive performance and milk yield. The service interval, service period,
days open, and calving interval were significantly (P < 0.05) longer in cows afflicted with dystocia compared to normal cows. The conception rate was lower (P < 0.05), but the number of service per conception was higher (P < 0.05) in cows afflicted with dystocia compared to normal cows (60.5% vs. 73.0% and 3.4 vs. 2.7, respectively). Average
daily milk yield was lower (P < 0.05) by 1 kg for cows with incidence of dystocia compared to normal cows. 相似文献
9.
Kamga-Waladjo Alain Richi Gbati Oubri Bassa Kone Philippe Lapo Rock Allister Chatagnon Gérard Bakou Serge N. Pangui Louis Joseph Diop Papa El Hassane Akakpo Justin Ayayi Tainturier Daniel 《Tropical animal health and production》2010,42(5):953-959
The aim of this study was to determine the seroprevalence of Neospora caninum antibodies and its effects on reproductive parameters in cows in intensive dairy herds in Dakar. Randomised blood samples
were taken for serology from 196 cows in four herds with a history of sporadic abortion. All of the sera were assayed for
antibodies against N. caninum, Candida guillermondii, Coxiella burnetii, and Chlamydophila sp. The associations between serostatus and reproductive parameters (abortion, number of inseminations to conception, and
calving to conception interval) were assessed over a period of 5 years (2004–2008). The seroprevalence of N. caninum antibodies in dairy cattle was 17.9%. The local Gobra breed and crossbreeds had higher levels of N. caninum antibodies than exotic breeds (p < 0.05). For the most recent pregnancies, seropositive cows required more inseminations to establish conception than seronegative
cows (p < 0.05). The results indicate that dairy cattle from Dakar are exposed to N. caninum. Neosporosis should, therefore, be systematically considered as a cause when the calving to conception interval is prolonged. 相似文献
10.
Hadi Atashi Mohammad Javad Zamiri Mohammad Bagher Sayyadnejad Amir Akhlaghi 《Tropical animal health and production》2012,44(8):2001-2006
The study was undertaken to determine the trends in the reproductive performance of Holstein dairy cows in Iran during 1994 to 2008. Reproductive performance data for 528,034 lactations of 246,132 cows in 1,822 Holstein dairy herds of Iran were used. The potential effect of calving season, herd, parity, calving year, as well as herd size and 305-day milk production on reproductive performance traits was investigated using multiple regression models. The least squares means of age at first calving decreased by 3.1 (±0.06) days per year from 806.5 (±96.3) days in 1994 to 788 (±89.9) days in 2008. The least squares means of calving interval increased 1.02 (±0.03) days per year from 394.1 (±65) days in 1994 to 413.2 (±81) days in 2008. Greater 305-day milk production was associated with an average increase of 6.55 (±0.08) days in calving interval per 1,000-kg increase in milk yield. Larger herd size was associated with an average decrease of 0.22 (±0.02) days in calving interval per 50 cows per herd. The mean number of days dry was 88.6 (±51.3) days and increased by 0.82 (±0.02) days per year. In conclusion, reproductive performance in Holstein dairy herds has generally decreased, whereas herd size and milk production have increased over time. Producers may make significant improvements in herd reproduction by reviewing management strategies including the sire selection, reproductive management, inseminator training and techniques, and improved estrous detection. Moreover, it may be advisable for the fertility traits to be included in the genetic selection indices to reduce the rate of reproductive decline. 相似文献
11.
The study is focused on the capability of artificial neural networks (ANNs) to predict next month and first lactation 305-day
milk yields (FLMY305) of Kenyan Holstein–Friesian (KHF) dairy cows based on a few available test days (TD) records in early
lactation. The developed model was compared with multiple linear regressions (MLR). A total of 39,034 first parity TD records
of KHF dairy cows collected over 102 herds were analyzed. Different ANNs were modeled and the best performing number of hidden
layers and neurons and training algorithms retained. The best ANN model had one hidden layer of logistic transfer function
for all models, but hidden nodes varied from 2 to 7. The R
2 value for ANNs for training, validation, and test data were consistently high showing that the models captured the features
accurately. The R
2, r, and root mean square were consistently superior for ANN than MLR but significantly different (p > 0.05). The prediction equation with four variables, i.e., first, second, third, and fourth TD milk yield, gave adequate
accuracy (79.0%) in estimating the FLMY305 from TD yield. It emerges from this study that the ANN model can be an alternative
for prediction of FLMY305 and monthly TD in KHF. 相似文献
12.
Bayissa B Ayelet G Kyule M Jibril Y Gelaye E 《Tropical animal health and production》2011,43(4):759-766
Cross-sectional serological study and questionnaire survey were conducted in Borana pastoral and agro-pastoral area to determine
seroprevalence and risk factors associated with foot-and-mouth disease (FMD) infection and to assess community perceptions
as to importance of the disease. A multistage random sampling was carried out to select cattle for seroprevalence and households
for interviews. Totally, 768 sera were collected from 111 herds. The overall individual level seroprevalence of 23.0% (n = 177) and herd level seroprevalence of 58.6% (n = 65) were recorded using 3ABC ELISA test. The variation of individual level seroprevalence in districts were statistically
significant (P < 0.05) which was 29.9% in Arero, 24.0% in Yabello, and 15.7% in Teltele. From multivariate logistic regression analysis,
herd size and age were seen to be significantly (P < 0.05) associated with FMD seroprevalence. The result of the questionnaire survey based on 120 respondents indicated that,
the daily milk yield of cows infected with FMD during outbreaks is reduced to an average of 0.5 L for 25.5 days while cows
developing heat-intolerance syndrome after acute infection gave an average 0.67 L for 3.8 months and their calving interval
prolonged about 12 months. The questionnaire survey in agro-pastoral area of Borena also indicated that FMD-infected oxen
remained off-plough for one season when outbreaks occur in cropping time, whereas heat-intolerant oxen were no longer used
for traction. These findings of the present study indicated that FMD is a highly prevalent and economically important disease
in the Borana pastoral and agro-pastoral production systems which need effective control strategy for the disease. 相似文献
13.
Ghavi Hossein-Zadeh N 《Tropical animal health and production》2011,43(6):1111-1115
Calving records from the Animal Breeding Center of Iran collected from January 1987 to December 2007 and comprising 292,875
calving events of Holsteins from 1,413 dairy herds were analyzed using univariate and bivariate linear animal models to estimate
heritabilities and genetic correlations for calving intervals in the first three lactations of Holstein cows. Genetic trends
were obtained by regressing yearly mean estimates of breeding values on calving year. Average calving intervals were from
406 to 414 days and decreased over the parities. Heritability estimates for calving intervals varied from 0.03 to 0.04 across
the parities. Also, estimates of genetic correlations between calving intervals in different parities were high and ranged
from 0.67 to 0.89. The average annual phenotypic trends obtained from fitting linear regression of annual mean calving intervals
at parity 1 and 2 were significant (P < 0.01), but the phenotypic trend of calving interval at parity 3 was not significant over the years. On the other hand,
there was an increasing genetic trend for calving interval at parity 1, and there were decreasing genetic trends for calving
intervals at parity 2 and 3 over the years (P < 0.01). The low estimates of heritability obtained in this study imply that much of the improvement in calving interval
traits could be attained by improvement of production environment rather than genetic selection. 相似文献
14.
Risk of removal and effects on milk production associated with paratuberculosis status in dairy cows
Lombard JE Garry FB McCluskey BJ Wagner BA 《Journal of the American Veterinary Medical Association》2005,227(12):1975-1981
OBJECTIVE: To determine effects on production and risk of removal related to Mycobacterium avium subsp paratuberculosis (MAP) infection at the individual animal level in dairy cattle. DESIGN: Longitudinal study. ANIMALS: 7,879 dairy cows from 38 herds in 16 states. PROCEDURE: A subset of dairy cattle operations that participated in the National Animal Health Monitoring System Dairy 2002 study was evaluated via a serum ELISA for antibodies against MAP and categorized according to ELISA score. Dairy Herd Improvement Association records were obtained to collect current and historical lactation data and removal (ie, culling) information. Production variables were evaluated on the basis of serum ELISA category. RESULTS: Cows with strong positive results had mature equivalent (ME) 305-day milk production, ME 305-day maximum milk production, and total lifetime milk production that were significantly lower than cows in other categories. No differences were observed for ME 305-day fat and protein percentages, age, lactation, and lactation mean linear somatic cell count score between cows with strong positive results and those with negative results. After accounting for lactation number and relative herd-level milk production, cows with strong positive results were significantly more likely to have been removed by 1 year after testing. CONCLUSIONS AND CLINICAL RELEVANCE: Without management changes designed to reduce the farm-level prevalence of MAP infection, paratuberculosis will continue to reduce farm income by decreasing milk production and potentially increasing premature removal from the herd. 相似文献
15.
Effect of polymorphisms at the STAT5A and FGF2 gene loci on reproduction, milk yield and lameness of Holstein cows 总被引:1,自引:0,他引:1
Oikonomou G Michailidis G Kougioumtzis A Avdi M Banos G 《Research in veterinary science》2011,91(2):235-239
The objective of this study was to investigate the association of polymorphisms at the STAT5A and FGF2 gene loci with fertility, lactation milk yield and lameness in dairy cattle. Five hundred and eighteen primiparous Holstein cows were included in the study. Several reproductive traits were considered including conception rate (0/1) at first insemination, conception rate (0/1) in a 305-day lactation, number of inseminations per conception, interval (days) from calving to conception for cows that conceived in the first 305 days of lactation and age at first calving. Milk yield and lameness incidence were also recorded. Genotyping was performed using PCR-RFLP. The effect of allele substitution at each gene locus on reproductive traits, milk yield and lameness was assessed with single-trait mixed linear models. No significant associations were found between reproduction traits and any of the studied polymorphisms, apart from age at first calving, for which STAT5A polymorphism had a suggestive effect (P = 0.077). In addition, no significant effect of any polymorphism on lameness was found. Replacement of the C by G allele at the STAT5A locus was associated with a significant (P < 0.05) increase in lactation milk yield, suggesting that this locus could be considered in gene assisted selection for the genetic improvement of milk production. 相似文献
16.
Ratanapob N Arunvipas P Kasemsuwan S Phimpraphai W Panneum S 《Tropical animal health and production》2012,44(4):741-745
The objectives of this study were to determine the prevalence and risk factors for intestinal parasite infection in goats
raised in Nakhon Pathom Province. Fecal samples from 190 goats in 12 herds were collected per rectum. Questionnaires focusing
on the general information about the farm and farmers, and management practices on farms were completed. Modified McMaster
counting technique was performed to detect eggs of intestinal parasites. Each egg found was classified into three groups of
parasites based on its characteristics. Individual and herd prevalence were calculated. Multiple logistic regressions were
performed to analyze risk factors of infection. Herd prevalence of intestinal parasite infection was 100%, while individual
prevalence was 79.47%. Strongyle group was the most common intestinal parasite found in this study. Moniezia spp. (8/190) and Trichuris spp. (1/190) were also found. The average number of eggs found was 1,176 eggs per gram of feces. Risk factors for intestinal
parasite infection were housing system, deworming interval, and type of goat in herd. Goats housed in groups had higher infection
rates compared with goats housed individually (odds ratio (OR) = 6.34; P value = 0.009). Goats in herds in which anthelmintic drugs were administered in intervals of greater than 3 months were more
likely to become infected with intestinal parasites (OR = 33.07; P value <0.001). Goats in herds that kept only dairy goats were less likely to become infected than herd that kept only meat
goats or kept both dairy and meat goats (OR = 46.20 and 8.75; P value <0.001 and 0.011, respectively). 相似文献
17.
Ansari-Lari M Haghkhah M Bahramy A Novin Baheran AM 《Tropical animal health and production》2009,41(4):553-557
A cross-sectional study was conducted from March to August 2006 in dairy herds in Fars province, southern Iran to determine
the herd-level risk factors for infection with Mycobacterium avium subspecies paratuberculosis (MAP). Statistical analysis using multivariable logistic regression showed that contamination of udders of periparturient
cows with manure (OR = 6.4, P = 0.02) and history of having suspected cases of Johne's disease in the herd (OR = 6.7, P = 0.04)
were significantly associated with the herd infection status. No relationship between breed, herd size and other management
practices with the infection status of the herd were found in this study. Implementing high sanitary measures in the farm,
particularly with respect to manure handling and cleaning could be considered as one of the important aspects in controlling
disease in the region as well as in the future educational effort. 相似文献
18.
R. M. Jacobs J. L. Heeney M. A. Godkin K. E. Leslie J. A. Taylor C. Davies V. E. O. Valli 《Veterinary research communications》1991,15(6):463-474
A newly developed milk dot blot test was used to detect anti-bovine leukaemia virus (BLV) antibody in milk samples from 2079 lactating adult cows from among 61 herds. The milk dot blot test was highly repeatable; the concordance rate, compared with the agar gel immunodiffusion test performed on serum, was 83.5%. All herds contained BLV-positive cows; the prevalence rate was 36%. BLV-positive cows tended to come from larger herds and were older and more often later in lactation. Fourteen production and related variables (herd size, age, days open, days in milk, milk somatic cell count, milk, fat, and protein produced in the current lactation, projected production of milk, fat, and protein, and breed class average deviations for milk, fat, and protein) were compared between BLV-positive and BLV-negative cows. Although somatic cell count, milk produced, and projected production of milk and protein were related significantly to BLV status using simple tests of association, once the variables herd size, age and days in milk were controlled, these differences were removed. Further analyses using logistic (outcome: individual cow BLV status) and least-squares regression (outcome:herd proportion of BLV-positive cows) failed to show an association between any of the measured production or related variables and BLV-positivity. We concluded that the effect of BLV on production and related variables in dairy cows was below the sensitivity of our analytical techniques or was non-existent.Abbreviations ABCA
herd average breed class average for milk, fat, and protein production
- AVGAGE
average age of the herd
- ADIM
herd average for days in milk
- AGID
agar gel immunodiffusion
- AVGSCC
herd average milk somatic cell count
- BCA
breed class average, a milk, fat and protein production index calculated by comparing a cow's actual 305-day lactation production to the corresponding BCA standard for the same breed, age, and month of calving
- BLV
bovine leukaemia virus
- CALVINT
calving interval
- COWAGE
cow age
- DBCA
breed class average deviation for milk, fat, and protein production, the difference between an individual cow's BCA and the herd average
- DIM
days in milk
- HS
herd size corresponding to the number of lactating cows in a herd
- LACT
actual amount of milk, fat, and protein produced in a cow's lactation
- ODHIC
Ontario Dairy Herd Improvement Corporation
- PCTPOS
percentage of herd that is BLV-positive
- PROJ
projected 305-day production for milk, fat, and protein by fitting to a standard lactation curve adjusted for days in milk and age at calving
- RHBCA
rolling herd average for breed class average for milk, fat, and protein production, the average for all cows that completed a lactation (cows must have completed a 305-day lactation) during the previous 12 months
- SCC
milk somatic cell count 相似文献
19.
Ram press sunflower cake protein concentrate was formulated locally and its effect on the performance of dairy cows was compared
with that of a commercial dairy concentrate. The effects of concentrate on roughage dry matter intake, milk yield and milk
composition, live weight and calving intervals were similar for all concentrates, which indicated that the home grown dairy
concentrates were as effective as the dairy commercial concentrate. The lack of significant differences in the concentrations
of rumen NH3-N, pH, VFAs and total AA in all the cows between concentrate types supported this. The results indicated that in the low-resource
and low-input production systems, crossbreds were as productive as Jersey and Red Dane cows. The exotic cows were more susceptible
to tick-borne diseases and mastitis, and showed higher incidences of calving problems and retained placenta compared with
crossbred cows. The economics of feeding ram press sunflower concentrate were compared with those of a commercial dairy concentrate
on the performance of crossbred, Red Dane and Jersey cows. The gross margin was higher when feeding sunflower cake than when
feeding commercial dairy concentrate (p < 0.05). 相似文献
20.
Effects of malic acid on feed intake, milk yield, milk components and metabolites in early lactation Holstein dairy cows 总被引:2,自引:0,他引:2
C. Wang Q. Liu W.Z. Yang Q. Dong X.M. Yang D.C. He K.H. Dong Y.X. Huang 《Livestock Science》2009,124(1-3):182-188
The objective of this study was to evaluate the effects of malic acid (MA) on feed intake, milk yield and composition, blood metabolites and energy balance in early lactation Holstein dairy cows from 1 to 63 day in milk (DIM). Twenty-eight multiparous Holstein dairy cows, blocked by lactation number, previous 305-d mature equivalent milk production, and expected calving date, were arranged into four groups in a randomized block design. Treatments were: control (without MA), LMA, MMA and HMA with 70, 140 and 210 g malic acid per cow per day, respectively. The supplement of food grade MA (99.8% of MA) was hand-mixed into the top one-third of the daily ration. Cows were fed ad libitum a total mixed ration consisting of equal proportion of forage and concentrate. Milk yield increased (P = 0.04), but feed intake and milk components were not affected (P > 0.05) by MA supplementation. The energy balance, expressed as the difference between energy input and output, tended to be higher (P = 0.08) for MA supplemented cows during the 63-DIM period MA and supplemented cows showed a trend (P = 0.07) toward less loss of BW during the 63-day period, especially during the first 21-day of lactation. Concentrations of plasma glucose and serum insulin were higher for cows fed LMA, MMA, and HMA relative to control and linearly (P < 0.01) increased with increasing MA supplementation. Concentrations of non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA) and urine ketones were lower for MA-supplemented cows at 7, 14 and 21 DIM of lactation and linearly (P < 0.01) decreased with increasing MA supplementation. Although feed intake was not affected, milk yield increased, MA-supplemented cows experienced higher concentrations of plasma glucose and serum insulin, lower concentrations of plasma BHBA and NEFA, and lower concentrations of urine ketones, suggesting that nutrient digestibilities and energy availability may have been improved. 相似文献