Livestock production science最新文献

{"title":"Breeding objectives for beef cattle used in different production systems","authors":"M. Wolfová ,&nbsp;J. Wolf ,&nbsp;R. Zahrádková ,&nbsp;J. Přibyl ,&nbsp;J. Daňo ,&nbsp;E. Krupa ,&nbsp;J. Kica","doi":"10.1016/j.livprodsci.2004.12.019","DOIUrl":"10.1016/j.livprodsci.2004.12.019","url":null,"abstract":"<div><p>A general bio-economic model for beef cattle production was used to define breeding objectives for Charolais cattle to be utilized in a variety of linked production systems. Economic weights were calculated for 16 traits (some with both direct and maternal components) in three production systems (pure-breeding and terminal crossing with beef or dairy cows) and two marketing strategies (sale or fattening of weaned surplus calves). Economic weights for the total breeding objective were calculated as weighted averages, where weights were numbers of cows expected to be mated with Charolais bulls in each production system and marketing strategy. Results suggest that the direct component of calving performance and cow longevity were of primary economic importance in all systems. Conception rate of cows and weaning weight reached about 50% of the standardized economic weight of calving performance in purebred systems with sale of weaned calves, whereas in purebred systems with fattening the economic importance of the direct component of cow conception rate, losses at calving, mature weight of cows, weaning weight, and fattening traits were of equal importance (each approximately about 20% that of calving performance). In terminal crossing systems, weaning weight was important when calves were sold at weaning, and fattening traits were important for systems selling fattened animals. The bio-economic model performed well under the conditions of this demonstration and could easily be customized for other applications.</p></div>","PeriodicalId":92934,"journal":{"name":"Livestock production science","volume":"95 3","pages":"Pages 217-230"},"PeriodicalIF":0.0,"publicationDate":"2005-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.livprodsci.2004.12.019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55263277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Acclimate™ on the frequency and duration of aggressive sequence and growth performance in co-mingled, weaned pigs","authors":"M. Amstutz,&nbsp;K. Bennett-Wimbush,&nbsp;T. Meek,&nbsp;S. Courtney","doi":"10.1016/j.livprodsci.2005.01.004","DOIUrl":"10.1016/j.livprodsci.2005.01.004","url":null,"abstract":"<div><p>Co-mingling weaned pigs often results in aggressive behavior which can result in injury and reduced performance. This experiment examined the effect of Acclimate™, a product reported to reduce equine aggression, on weaned pig aggression and growth performance. Weanling pigs (<em>n</em>=214, avg. wt.=5.93 kg) were blocked by weight, sex and litter (<em>n</em>=25) and randomly assigned to either Acclimate™ treatment or a control group. Acclimate™ treated pigs were marked on the nose, face and neck. Pigs were individually identified and videotaped to determine frequency of aggressive sequence (FAS) and duration of aggression (DOA) on an individual pig basis. Pig weights and feed consumption were used to determine feed intake, total weight gain (TWG), average daily gain (ADG) and feed to gain ratio (F/G). Differences between litter, sex and treatment for FAS, DOA, F/G and ADG were tested using GLM, SAS. Neither Acclimate™ treatment or sex had a significant effect on FAS, TWG or F/G. However, there was a trend towards reduced duration and intensity of aggression in Acclimate™ treated pigs (<em>p</em>=0.1). There was a significant effect of litter (<em>p</em>&lt;0.01) and TWG (<em>p</em>&lt;0.001) on FAS at both 1 and 3 weeks. Acclimate™ treatment of weaned pigs does not decrease FAS, but may decrease the intensity and duration of aggression without negatively effecting growth.</p></div>","PeriodicalId":92934,"journal":{"name":"Livestock production science","volume":"95 3","pages":"Pages 243-246"},"PeriodicalIF":0.0,"publicationDate":"2005-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.livprodsci.2005.01.004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55263345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stress parameters and immune response of layers under different cage floor and density conditions","authors":"E.E. Onbaşılar,&nbsp;F.T. Aksoy","doi":"10.1016/j.livprodsci.2005.01.006","DOIUrl":"10.1016/j.livprodsci.2005.01.006","url":null,"abstract":"<div><p>The aim of the experiment was to investigate the effects of cage floor and cage density on stress parameters of laying hens. A total of 162 brown laying hens (Hyline Brown), aged 34 weeks, were used in the experiment. Compact-type battery cages, with three floors, were used. Hens were allocated as one, three or five hens in each of 18 cages to obtain three different cage density groups of 1968, 656 and 393.8 cm² floor area per hen, respectively. The same number of cages with different cage density were allocated to three different battery floors (first floor=top, second=middle, third=bottom) systematically. Values for body weight, mortality rate, egg weight, egg production, egg quality characteristics, egg yolk cholesterol content, the levels of blood plasma corticosterone, serum glucose, total cholesterol and triglycerides, the ratio of heterophils to lymphocytes (H–L ratio), antibody titers, claw length score, foot health score, plumage score and throat skin injuries were taken as indicators of stress. The values for egg weight (<em>P</em>&lt;0.01) at the first floor were greater than the other floor levels. The group with five hens per cage had significantly lower mean estimates (<em>P</em>&lt;0.01) than other groups with respects to body weight (<em>P</em>&lt;0.001), egg production (<em>P</em>&lt;0.001), egg weight (<em>P</em>&lt;0.001) and plumage score (<em>P</em>&lt;0.01), while significantly higher mean estimates for egg albumen index (<em>P</em>&lt;0.01), Haugh unit (<em>P</em>&lt;0.01), serum glucose (<em>P</em>&lt;0.001), and H–L ratio (<em>P</em>&lt;0.001). Serum cholesterol was higher in cages with one hen than that with five hens, whereas plasma corticosterone was lower. Antibody titers in cages with one hen was similar to that with three or five hens; however, those with three hens had higher titers than those with five hens. Values for egg breaking strength, yolk index, egg cholesterol content, and foot health score were not affected by cage density or floor. The results suggest that the allocation of three hens per cage had no measurable effect on health and welfare.</p></div>","PeriodicalId":92934,"journal":{"name":"Livestock production science","volume":"95 3","pages":"Pages 255-263"},"PeriodicalIF":0.0,"publicationDate":"2005-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.livprodsci.2005.01.006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55263367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pedigree analysis in the Andalusian horse: population structure, genetic variability and influence of the Carthusian strain","authors":"M. Valera ,&nbsp;A. Molina ,&nbsp;J.P. Gutiérrez ,&nbsp;J. Gómez ,&nbsp;F. Goyache","doi":"10.1016/j.livprodsci.2004.12.004","DOIUrl":"10.1016/j.livprodsci.2004.12.004","url":null,"abstract":"<div><p>The studbook of the Andalusian horse comprising a total of 75,389 individuals (6318 of them classified as Carthusians) was analysed in order to ascertain the genetic history of the breed and, specially, to evaluate its genetic variability and the influence of the Carthusian strain in the breed. Although there is no possible way to identify studs acting as Nucleus in the breed, there is a high concentration of genes and individuals' origin. The effective number of studs producing grandfathers was of 10.6. The equivalent number of founders was 1948.5 individuals (370.5 Carthusians). The effective number of founders was 39.6 and the effective number of ancestors 27. Only 6 ancestors were necessary to explain 50% of the genetic variability of the breed. The average values of inbreeding and average relatedness for the whole Andalusian horse population were, respectively, 8.48% and 12.25%. The same values for the Carthusian strain were higher (9.08% and 13.01%) even thought the generation interval for the strain was larger than that for the whole population (12.43 versus 10.11 years). In any case, inbreeding in Andalusian horse breed seems to have a remote origin and linked to the Carthusian individuals. The total contribution of the Carthusian founders to the populations accounted for up to 87.64% of the population. In turn the Carthusian ancestors explained 80.46% of the genetic variability of the breed. No differentiation was found between Carthusian and non-Carthusian reproductive individuals using genealogical <em>F</em>_ST (0.000026). It can be concluded that the distinction between Carthusian and non-Carthusian individuals within the Andalusian horse breed does not have genetic support. The unbalanced use of the Carthusian individuals with lower average relatedness values for reproduction is proposed to preserve the genetic variability of the breed.</p></div>","PeriodicalId":92934,"journal":{"name":"Livestock production science","volume":"95 1","pages":"Pages 57-66"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.livprodsci.2004.12.004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55262508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Consequences of selection for growth on carcass and meat quality in Pirenaica cattle","authors":"J. Altarriba ,&nbsp;L. Varona ,&nbsp;C. Moreno ,&nbsp;G. Yagüe ,&nbsp;C. Sañudo","doi":"10.1016/j.livprodsci.2004.12.008","DOIUrl":"10.1016/j.livprodsci.2004.12.008","url":null,"abstract":"<div><p>The male progeny of nine bulls used in artificial insemination were sampled to determine the effects of selection for weight at 210 days of age (<em>W</em>₂₁₀) on carcass and meat quality in the Pirenaica cattle breed. For each of the 125 male offspring raised in experimental conditions, we measured 38 variables (<em>y</em>) defining carcass and meat quality. In turn, the breeding values of those animals for the <em>W</em>₂₁₀ trait (<em>û</em>₂₁₀) were calculated without their own record and without data of maternal siblings. Indirect responses were estimated from the slope of the covariate between the selection index (<em>û</em>₂₁₀) and the phenotype of those variables (<em>b</em>(<em>y</em>, <em>û</em>₂₁₀)). We derived that the covariate depends on the genetic correlation and the genetic variances of the selection index and the trait. Consequently, this method provides an unbiased estimator of the correlated response, without requiring an estimate of the genetic correlation. We conclude that, in the Pirenaica breed, selection for <em>W</em>₂₁₀ produces animals with higher live- and carcass weights at slaughter, wider carcasses, deeper and longer legs with a greater perimeter, and greater loin surface. Genetic changes were not detected in dressing percentage and physicochemical or sensorial parameters of meat quality.</p></div>","PeriodicalId":92934,"journal":{"name":"Livestock production science","volume":"95 1","pages":"Pages 103-114"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.livprodsci.2004.12.008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55262766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Association between PrP genotypes and performance traits in an experimental Dutch Texel herd","authors":"J.H. Brandsma,&nbsp;L.L.G. Janss,&nbsp;A.H. Visscher","doi":"10.1016/j.livprodsci.2004.12.011","DOIUrl":"10.1016/j.livprodsci.2004.12.011","url":null,"abstract":"<div><p>The Dutch scrapie eradication programme for sheep is based on selection for the resistant ARR/ARR genotype of the ovine prion protein (PrP) gene. The aim of this study was to estimate the possible association of the PrP genotype and performance traits. The data included 963 genotyped females born between 1991 and 1998 in an experimental Texel flock, in which the Booroola gene was introgressed. The associations of the PrP gene were evaluated using a single trait animal model. The allele frequency from the herd mostly corresponds with genotyped rams in the Netherlands in the same period. The results indicate no significant associations with litter size, and only 3 of 112 estimated associations with weight, growth and body measurements were significant, with a low significance level. Therefore it can be concluded that selection for ARR/ARR rams in this experimental herd seem to have no effect on the performance traits due to association. The included data from this study is compared to data from other studies estimating associations between PrP genotype and performance traits. The comparison suggests of a possible small effect, which is only detectable in large datasets, which could be a result of linkage to the PrP genotype.</p></div>","PeriodicalId":92934,"journal":{"name":"Livestock production science","volume":"95 1","pages":"Pages 89-94"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.livprodsci.2004.12.011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55262936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of protein degradation characteristics and metabolisable protein of elephant grass (Pennisetum purpureum) and locally available protein supplements","authors":"F. Kabi ,&nbsp;F.B. Bareeba ,&nbsp;Ø. Havrevoll ,&nbsp;I.D.T. Mpofu","doi":"10.1016/j.livprodsci.2004.12.013","DOIUrl":"10.1016/j.livprodsci.2004.12.013","url":null,"abstract":"<div><p><span>Degradation characteristics of crude protein (CP) and metabolisable protein (MP) of feeds for early-weaned, growing and finishing beef bulls were evaluated in three experiments. Feeds in experiment 1 were fresh elephant grass (FEG) and molasses supplemented with sweet potato vines (SPV) in diet 1, supplemental (GCM) compounded from gliricidia, cottonseed cake (CSC), maize bran and NaCl in diet 2 and a commercial concentrate (CC) in diet 3. Feeds in experiment 2 were basal maize stover mixed with molasses (MSM) and FEG supplemented with SPV in diet 1, GCM in diet 2 and CC in diet 3. In experiment 3, MSM and FEG were supplemented with compounded supplemental protein feeds with varying levels of gliricidia inclusion. Supplemental (GM) containing gliricidia, maize bran and NaCl were used in diet 1, GCM in diet 2 and supplemental (CM) containing CSC, maize bran and NaCl in diet 3. Degradabilities of experimental feeds were measured at 0, 6, 12, 24, 48, 72, 96, and 120 h by the nylon bag technique using two rumen fistulated steers (300±10 kg). Effective CP degradabilities of FEG in the three experiments varied (</span><em>P</em>&lt;0.05) with the supplements. In experiment 1, effective CP degradabilities of the supplements varied (<em>P</em>&lt;0.05) from 668.3 g kg⁻¹ CP in CC to 722.1 g kg⁻¹ CP in SPV and 743.7 g kg⁻¹ CP in GCM. Effective rumen degradable protein (ERDP), digestible udegradable protein (DUP) and MP varied (<em>P</em>&lt;0.05) among the supplements. In experiment 2, effective CP degradabilities of the supplements did not vary but ERDP varied (<em>P</em>&lt;0.05) from 83.7 g kg⁻¹ CP in SPV to 116.6 g kg⁻¹ CP in GCM and 123.8 g kg⁻¹ CP in CC and MP followed similar trends. In experiment 3, effective CP degradabilities of the supplements decreased (<em>P</em>&lt;0.05) with increasing gliricidia inclusion. ERDP increased (<em>P</em>&lt;0.05) with lower gliricidia while DUP varied (<em>P</em>&lt;0.05) from 18.2 g kg⁻¹ CP in CM to 23.6 g kg⁻¹ CP in GCM and 36.6 g kg⁻¹ CP in GM. These data have shown that the majority of locally available feeds evaluated in this study are not similar in CP degradation characteristics and MP but compounded GCM is more suitable in providing degradable and undegradable protein for beef bulls in Uganda.</p></div>","PeriodicalId":92934,"journal":{"name":"Livestock production science","volume":"95 1","pages":"Pages 143-153"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.livprodsci.2004.12.013","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55263023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relationships of plasma insulin-like growth factor (IGF)-I and IGF-II concentrations to growth in purebred Landrace and Yorkshire female pigs","authors":"C.Y. Lee ,&nbsp;K.H. Baik ,&nbsp;B.-C. Park ,&nbsp;H.C. Park","doi":"10.1016/j.livprodsci.2005.01.002","DOIUrl":"10.1016/j.livprodsci.2005.01.002","url":null,"abstract":"<div><p>The present study was undertaken to investigate the relationships of plasma insulin-like growth factor (IGF)-I and IGF-II concentrations during the growing period to multiple growth measures and estimates at 90-kg body weight (BW) and thereby to evaluate plasma IGF concentrations as potential indicators for the growth measure in the pig. Jugular blood samples were obtained from 151 Landrace and 241 Yorkshire female pigs, which had been born of approximately equal numbers of a low (&lt;<em>μ</em>−0.5S.D.)– and a high (&gt;<em>μ</em>+0.5S.D.)–ADG line dams in each breed, at 25-, 60- and 90-kg BW. Backfat thickness (BFT), loin muscle area (LMA) and lean percentage were measured or estimated by ultrasonography at 90-kg BW, after which breeding values for ADG (ADG-BV) and BFT (BFT-BV) were predicted. Plasma IGF-I concentration at 25-kg BW was correlated with BFT in Landrace (<em>r</em>=0.26; <em>P</em>&lt;0.01); in Yorkshire, these two variables tended to be correlated (<em>r</em>=0.12; <em>P</em>=0.09). Plasma IGF-I concentration at this BW was also correlated (<em>P</em>&lt;0.01) with BFT-BV (<em>r</em>=0.29 and 0.30 in Landrace and Yorkshire, respectively; <em>P</em>&lt;0.01) and also with the lean percentage (<em>r</em>=−0.25, <em>P</em>&lt;0.05 in Landrace; <em>r</em>=−0.25, <em>P</em>&lt;0.01 in Yorkshire). Plasma IGF-I concentration at 60 kg was positively correlated (<em>P</em>&lt;0.01) with ADG (<em>r</em>=0.36) as well as ADG-BV (<em>r</em>=0.40) in Landrace, whereas in Yorkshire, IGF-I concentration at this BW was correlated with ADG only (<em>r</em>=0.21; <em>P</em>&lt;0.01). Plasma IGF-II concentration at 60-kg BW was correlated with ADG and ADG-BV in Landrace, but in Yorkshire, the ADG-BV was correlated with IGF-II concentration at 25-kg BW. In conclusion, plasma IGF-I concentration during the growing period is indicative of the growth potential to some extent in purebred Landrace and Yorkshire female pigs.</p></div>","PeriodicalId":92934,"journal":{"name":"Livestock production science","volume":"95 1","pages":"Pages 163-169"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.livprodsci.2005.01.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55263319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparing risk perceptions and risk management in organic and conventional dairy farming: empirical results from Norway","authors":"O. Flaten ,&nbsp;G. Lien ,&nbsp;M. Koesling ,&nbsp;P.S. Valle ,&nbsp;M. Ebbesvik","doi":"10.1016/j.livprodsci.2004.10.014","DOIUrl":"10.1016/j.livprodsci.2004.10.014","url":null,"abstract":"<div><p>This study was conducted to explore organic and conventional dairy farmers' perceptions of risk and risk management, and to examine relationships between farm and farmer characteristics, risk perceptions, and strategies. The data originate from a survey of conventional (<em>n</em>=363) and organic (<em>n</em>=162) dairy farmers in Norway. Organic farmers had the least risk averse perceptions. Institutional and production risks were perceived as primary sources of risk, with farm support payments at the top. Compared to their conventional colleagues, organic farmers gave more weight to institutional factors related to their production systems. Conventional farmers were more concerned about costs of purchased inputs and animal welfare policy. Organic and conventional farmers' management responses were more similar than their risk perceptions. Financial measures such as liquidity and costs of production, disease prevention, and insurance were perceived as important ways to handle risk. Even though perceptions were highly farmer-specific, a number of socio-economic variables were found to be related to risk and risk management. The primary role of institutional risks implies that policy makers should be cautious about changing policy capriciously and they should consider the scope for strategic policy initiatives that give farmers some greater confidence about the longer term. Further, researchers should pay more attention to institutional risks.</p></div>","PeriodicalId":92934,"journal":{"name":"Livestock production science","volume":"95 1","pages":"Pages 11-25"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.livprodsci.2004.10.014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55260553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of dietary fish oil on conjugated linoleic acid, omega-3 and other fatty acids in milk fat from grazing dairy cows","authors":"O.A. Rego ,&nbsp;H.J.D. Rosa ,&nbsp;P. Portugal ,&nbsp;R. Cordeiro ,&nbsp;A.E.S. Borba ,&nbsp;C.M. Vouzela ,&nbsp;R.J.B. Bessa","doi":"10.1016/j.livprodsci.2004.11.040","DOIUrl":"10.1016/j.livprodsci.2004.11.040","url":null,"abstract":"<div><p>The main objective of this study was to evaluate the effect of supplementation with fish oil on fatty acid (FA) composition of milk fat from grazing dairy cows with particular emphasis on omega-3 and conjugated linoleic acid. Twelve dairy cows in mid-lactation were blocked by live weight, days in lactation and milk production and randomly assigned to the experimental groups corresponding to 3 different feeding regimens which were applied 3 times with 28-day duration according to a Latin square design. Cows were stocked at 2.5 heads per hectare and supplemented with 4 kg concentrate/cow/day (C), concentrate mixed with 160 g sardine oil (LFO) and concentrate mixed with 320 g sardine oil (HFO). Supplementation with fish oil (FO) resulted in a significant (<em>P</em>&lt;0.05) decrease in milk production and milk fat content and production. Supplementation with 320 g FO decreased (<em>P</em>&lt;0.05) milk protein content and production. The ratio protein/fat in milk increased with the level of FO supplemented (<em>P</em>&lt;0.05). Significant correlations were detected between some FA in milk fat and milk fat content. FO supplementation had no effect on concentration of medium chain FA but originated a decrease (<em>P</em>&lt;0.05) in concentration of short and long chain FA in milk fat. The sum of saturated FA decreased (<em>P</em>&lt;0.05) with the inclusion of FO in diet while the sum of unsaturated FA remains unchanged. Proportions of stearic and oleic FA in milk fat decreased and <em>trans</em>-vaccenic FA increase with FO supplementation (<em>P</em>&lt;0.05). Milk fat concentration of polyunsaturated n-3 FA was higher in treatment HFO. Concentration of very long chain omega FA in milk fat (i.e. C20:5-EPA e C22:6-DHA) increased by 2.7-fold with 160 g FO and by 5- to 7-fold with 320 g FO. However, the level of transfer efficiency of these FA from FO to milk fat was only 3.3% in treatment LFO and 4.0% in treatment HFO. CLA concentrations in milk fat were particularly high in this experiment and increased with the level of FO supplementation (<em>P</em>&lt;0.05).</p></div>","PeriodicalId":92934,"journal":{"name":"Livestock production science","volume":"95 1","pages":"Pages 27-33"},"PeriodicalIF":0.0,"publicationDate":"2005-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.livprodsci.2004.11.040","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55262371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}