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Genetic correlations between energy status indicator traits and female fertility in primiparous Nordic Red Dairy cattle
- T. Mehtiö, P. Mäntysaari, E. Negussie, A.-M. Leino, J. Pösö, E. A. Mäntysaari, M. H. Lidauer
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Inclusion of feed efficiency traits into the dairy cattle breeding programmes will require considering early lactation energy status to avoid deterioration in health and fertility of dairy cows. In this regard, energy status indicator (ESI) traits, for example, blood metabolites or milk fatty acids (FAs), are of interest. These indicators can be predicted from routine milk samples by mid-IR reflectance spectroscopy (MIR). In this study, we estimated genetic variation in ESI traits and their genetic correlation with female fertility in early lactation. The data consisted of 37 424 primiparous Nordic Red Dairy cows with milk test-day records between 8 and 91 days in milk (DIM). Routine test-day milk samples were analysed by MIR using previously developed calibration equations for blood plasma non-esterified FA (NEFA), milk FAs, milk beta-hydroxybutyrate (BHB) and milk acetone concentrations. Six ESI traits were considered and included: plasma NEFA concentration (mmol/l) either predicted by multiple linear regression including DIM, milk fat to protein ratio (FPR) and FAs C10:0, C14:0, C18:1 cis-9, C14:0 * C18:1 cis-9 (NEFAFA) or directly from milk MIR spectra (NEFAMIR), C18:1 cis-9 (g/100 ml milk), FPR, BHB (mmol/l milk) and acetone (mmol/l milk). The interval from calving to first insemination (ICF) was considered as the fertility trait. Data were analysed using linear mixed models. Heritability estimates varied during the first three lactation months from 0.13 to 0.19, 0.10 to 0.17, 0.09 to 0.14, 0.07 to 0.10, 0.13 to 0.17 and 0.13 to 0.18 for NEFAMIR, NEFAFA, C18:1 cis-9, FPR, milk BHB and acetone, respectively. Genetic correlations between all ESI traits and ICF were from 0.18 to 0.40 in the first lactation period (8 to 35 DIM), in general somewhat lower (0.03 to 0.43) in the second period (36 to 63 DIM) and decreased clearly (−0.02 to 0.19) in the third period (64 to 91 DIM). Our results indicate that genetic variation in energy status of cows in early lactation can be determined using MIR-predicted indicators. In addition, the markedly lower genetic correlation between ESI traits and fertility in the third lactation month indicated that energy status should be determined from the first test-day milk samples during the first 2 months of lactation.
Non-invasive individual methane measurement in dairy cows
- E. Negussie, J. Lehtinen, P. Mäntysaari, A. R. Bayat, A.-E. Liinamo, E. A. Mäntysaari, M. H. Lidauer
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Attempts to lower the environmental footprint of milk production needs a sound understanding of the genetic and nutritional basis of methane (CH4) emissions from the dairy production systems. This in turn requires accurate and reliable techniques for the measurement of CH4 output from individual cows. Many of the available measurement techniques so far are either slow, expensive, labor intensive and are unsuitable for large-scale individual animal measurements. The main objectives of this study were to examine and validate a non-invasive individual cow CH4 measurement system that is based on photoacoustic IR spectroscopy (PAS) technique implemented in a portable gas analysis equipment (F10), referred to as PAS-F10 method and to estimate the magnitude of between-animal variations in CH4 output traits. Data were collected from 115 Nordic Red cows of the Minkiö experimental dairy farm, at the Natural Resources Institute Finland (Luke). Records on continuous daily measurements of CH4, milk yield, feed intake and BW measurements over 2 years period were compiled for data analysis. The daily CH4 output was calculated using carbon dioxide as a tracer method. Estimates from the non-invasive PAS-F10 technique were then tested against open-circuit indirect respiration calorimetric chamber measurements and against estimates from other widely used prediction models. Concordance analysis was used to establish agreement between the chamber and PAS-F10 methods. A linear mixed model was used for the analysis of the large continuous data. The daily CH4 output of cows was 555 l/day and ranged from 330 to 800 l/day. Dry matter intake, level of milk production, lactation stage and diurnal variation had significant effects on daily CH4 output. Estimates of the daily CH4 output from PAS-F10 technique compared relatively well with the other techniques. The concordance correlation coefficient between combined weekly CH4 output estimates of PAS-F10 and chamber was 0.84 with lower and upper confidence limits of 0.65 and 0.93, respectively. Similarly, when chamber CH4 measurements were predicted from PAS-F10 measurements, the mean of two separate weekly PAS-F10 measurements gave the lowest prediction error variance than either of the separate weekly PAS-F10 measurements alone. This suggests that every other week PAS-F10 measurements when combined would improve the estimation of CH4 output with PAS-F10 technique. The repeatability of daily CH4 output from PAS-F10 technique ranged from 0.40 to 0.46 indicating that some between-animal variation exist in CH4 output traits.
Genetic control of greenhouse gas emissions
- Y. de Haas, P. C. Garnsworthy, B. Kuhla, E. Negussie, M. Pszczola, E. Wall, J. Lassen
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- Advances in Animal Biosciences / Volume 7 / Issue 2 / October 2016
- Published online by Cambridge University Press:
- 19 October 2016, pp. 196-199
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- October 2016
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Climate change is a growing international concern, and it is well established that the release of greenhouse gases (GHG) is a contributing factor. So far, within animal production, there is little or no concerted effort on long-term breeding strategies to mitigate against GHG from ruminants. In recent years, several consortia have been formed to collect and combine data for genetic evaluation. The discussion areas of these consortia focus on (1) What are methane-determining factors, (2) What are genetic parameters for methane emissions, (3) What proxies can be used, and what is their association with methane emission, and (4) How to move on with breeding for lower emitting animals? The methane-determining factors can be divided into four groups: (1) rumen microbial population, (2) feed intake and diet composition, (3) host physiology and (4) host genetics. The genetic parameters show that enteric methane is a heritable trait, and that it is highly genetically correlated with dry matter intake. So far, the most useful proxies relate to feed intake, milk mid IR spectral data and fatty acids in the milk. To be able to move on with a genetic evaluation and ranking of animals for methane emission, it is crucial to make measurements on commercial farms. In order to make that possible, it will be necessary to develop phenotypes that can be used by the farmer to optimise the production on farm level. Also, it is crucial to develop equipment that makes it possible to make measurements without interfering with everyday routines or identify proxies that are highly related to methane and which could easily be measured on a large scale. International collaboration is essential to make progress in this area. This is both in terms of sharing ideas, experiences and phenotypes, but also in terms of coming to a consensus regarding what phenotype to collect and to select for.
Growth and carcass composition of tropical fat-tailed Menz and Horro sheep breeds
- E. Negussie, O. J. Rottmann, F. Pirchner, J. E. O. Rege
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- Journal:
- Animal Science / Volume 78 / Issue 2 / April 2004
- Published online by Cambridge University Press:
- 18 August 2016, pp. 245-252
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- April 2004
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The pattern of growth and carcass composition of indigenous Ethiopian fat-tailed Menz and Horro lambs were assessed through serial slaughter and carcass dissection of 147 lambs at five different growth phases. The GLM procedure of Statistical Analysis Systems Institute and allometric growth equations were used to assess the effects of various factors and differential growth of carcass components, respectively. Results showed that the growth and carcass composition of Menz and Horro lambs was significantly (P < 0.05 to P < 0.001) affected by the genotype, growth phase and season of birth of lambs. The effects of growth phase clearly showed that slower growth of the body and of carcass components was observed during the third phase (i.e. after weaning). Although there was an effect on fat to lean ratios (P < 0.05), growth phase had no significant effect on dressing out proportion, and lean to bone ratios. A significant influence of genotype (P < 0.001) and sex (P < 0.05) on lean to bone ratios indicated that the Horro sheep and ram lambs had a much more developed and heavier skeleton than the Menz sheep and ewe lambs. Higher pre-slaughter, hot carcass, lean and bone and fat weights of May/June born lambs revealed significant advantages of wet season lambing for fast growth and improved carcass composition. The log/log regression of weights of dissectible carcass components on hot carcass and empty body weight showed that the differential growth of bone was declining and that of lean was isometric relative to the growth of empty body weight. For carcass fat, the allometric growth coefficients (b) of 1.5 and 1.8 for Menz and Horro sheep, respectively indicated that fat is a late maturing body component. Moreover the growth of carcass fat relative to empty body weight in the Menz and Horro sheep is slower than that reported for tropical sheep breeds.
Factors affecting reproductive performance and estimates of genetic parameters of litter size in Horro sheep
- S. ABEGAZ, G. DUGUMA, E. NEGUSSIE, U. GELMESA, F. TEREFE, J. E. O. REGE
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- Journal:
- The Journal of Agricultural Science / Volume 139 / Issue 1 / August 2002
- Published online by Cambridge University Press:
- 15 October 2002, pp. 79-85
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Conception and lambing rate, and litter size were studied on data from a flock of Horro sheep. The CATMOD and GLM procedures of SAS were used for the analysis of these traits. A sire, direct additive genetic and a repeatability animal model were employed to obtain estimates of heritability and repeatability for litter size. The results obtained showed that year of mating, age and weight of ewes at mating and number of previous parities had significantly (P<0.01) affected the rate of conception and lambing while weight of rams at mating has shown no significant effect (P>0.05). An increase in both conception and lambing rates was observed with the increase in weight of ewes up to about 36 kg and declined thereafter. Ewes which previously had no or one parity had lower conception and lambing rates compared with ewes in later parities. However, a decline in both conception and lambing rates was also observed in old ewes. Year of lambing, parity and weight of ewes at mating had a highly significant (P<0.01) effect on litter size. The overall mean litter size in the flock was 1.34 with annual means ranging from 1.18 to 1.55. Litter size increased with parity from 1.26 in primiparous ewes to 1.44 for ewes of parities five and above. With respect to weight of ewes at mating, litter size increased by 2.5% for each kg increase in weight at mating. The estimates of direct heritability (h2) for litter size were 0.17, 0.11 and 0.06 under the sire, direct animal and repeatability models. Repeatability was estimated to be 0.12. Since heritability and repeatability estimates of litter size are low, genetic improvement by selection may not bring sizeable impact in increasing litter size. Therefore flock management for optimal age structure and optimal weight of ewes at mating should receive due consideration to improve rates of conception, lambing and litter size in Horro sheep.