Relationship of Somatic Cell Count with Milk Yield and Composition in Chinese Holstein Population

The objective of this study was to analyze the relationship of somatic cell count （SCC） with milk yield, fat and protein percentage, fat and protein yield using analysis of variance and correlation analysis in Chinese Holstein population. The 10 524 test-day records of 568 Chinese Holstein Cattle were obtained from 2 commercial herds in Xi＇an region of China during February 2002 to March 2009. Milk yield, fat percentage, fat and protein yield initially increased and then dropped down with parity, whereas protein percentage decreased and SCC increased. Analysis of variance showed highly significant effects of different subclasses SCC on milk yield and composition （P〈 0.01）. Compared with milk yield with SCC ≤ 200 000 cells mL-1, milk yield losses with SCC of 200 000-500 000 cells mL-1, 501000-1 000 000 cells mL-1, ≥ 1 000 000 cells mL-1 were 0.387, 0.961 and 2.351 kg, respectively. The highly significant negative correlation coefficient between somatic cell score （SCS） and milk and protein yield, milk yield and fat and protein percentage, protein percentage and fat yield were -0.084, -0.037, -0.061, -0.168, and -0.088, respectively （P〈 0.01）. The highly significant positive correlation coefficients between SCS and fat yield and fat and protein percentage, milk yield and fat and protein yield, fat percentage and protein percentage and fat yield, protein yield and protein percentage and fat yield were 0.041, 0.177, 0.105, 0.771, 0.865, 0.122, 0.568, 0.318, and 0.695, respectively （P〈 0.01）. There was no significant relationship between fat percentage and protein yield （P 〉 0.05）. The results of the present study first time provide the relevant base-line data for assessing milk production at Xi＇an region of China.

Dietary supplementation with branchedchain amino acids enhances milk production by lactating sows and the growth of suckling piglets

Background:Under current dietary regimens,milk production by lactating sows is insufficient to sustain the maximal growth of their piglets.As precursors of glutamate and glutamine as well as substrates and activators of protein synthesis,branched-chain amino acids(BCAAs)have great potential for enhancing milk production by sows.Methods:Thirty multiparous sows were assigned randomly into one of three groups:control(a corn-and soybean meal-based diet),the basal diet+1.535%BCAAs;and the basal diet+3.07%BCAAs.The ratio(g/g)among the supplemental L-isoleucine,L-leucine and L-valine was 1.00:2.56:1.23.Diets were made isonitrogenous by the addition of appropriate amounts of L-alanine.Lactating sows had free access to drinking water and their respective diets.The number of live-born piglets was standardized to 9 per sow at d 0 of lactation(the day of parturition).On d 3,15 and 29 of lactation,body weights and milk consumption of piglets were measured,and blood samples were obtained from sows and piglets 2 h and 1 h after feeding and nursing,respectively.Results:Feed intake did not differ among the three groups of sows.Concentrations of asparagine,glutamate,glutamine,citrulline,arginine,proline,BCAAs,and many other amino acids were greater(P<0.05)in the plasma of BCAA-supplemented sows and their piglets than those in the control group.Compared with the control,dietary supplementation with 1.535%and 3.07%BCAAs increased(P<0.05)concentrations of free and protein-bound BCAAs,glutamate plus glutamine,aspartate plus asparagine,and many other amino acids in milk;milk production by 14%and 21%,respectively;daily weight gains of piglets by 19%and 28%,respectively,while reducing preweaning mortality rates by 50%and 70%,respectively.Conclusion:Dietary supplementation with up to 3.07%BCAAs enhanced milk production by lactating sows,and the growth and survival of their piglets.

The Effects of Graded Abomasal Glucose Infusion on Milk Yield and Composition in Lactating Goats

Four non-pregnant multiparous lactating goats were used in a 4 × 4 latin square experiment in the present study. The four treatments were abomasal infusion of 0, 50, 100, and 150 g d^-1 glucose. The results showed that graded glucose infusion increased milk yield （P 〈 0.01）. The highest milk yield was observed when 50 g d^-1 glucose was infused. An infusion of glucose at 100 or 150 g d^-1 failed to increase milk yield further and milk yield of the 100 g d ^-1 glucose infusion treatment was even significantly lower than that of the 50 g d^-1 treatment （P 〈 0.01）. Though milk fat content was gradually decreased by graded glucose infusions and milk fat yield of the 100 and 150 g d 1 treatments were lower than that of the control （P 〈 0.01）; milk fat yield of the 50 g d i treatment was not depressed and was higher than that of the control （P 〈 0.01）. Graded glucose infusion did not change the contents of milk protein and non-fatty solids. Yields of milk protein （P 〈 0.05）, lactose （P 〈 0.01）, non-fat solids （P 〈 0.01）, and lactose content （P 〈 0.01） of the 50 g d^-1 treatment were higher than those of the control but had no difference among the other three treatments. Contents of those de novo synthesized fatty acids in milk fat remained unchanged or increased and those preformed fatty acids remained unchanged or decreased by graded glucose infusion. Glucose infusion decreased the total yields of C16 ＋ C16：1 and 〉 C16 fatty acids and had no influence on the yield of C4-C14：1 fatty acids （P 〈 0.05）. Results of the present study implied that increased glucose supply had positive effects on the production of milk, milk protein, milk fat, and lactose only when glucose was a limiting factor for milk synthesis. Excessive glucose supply had no further beneficial effects and might depress milk fat synthesis.

Milk Yield of Holstein Cows Induced into Lactation Twice Consecutively and Lactation Curve Models Fitted to Artificial Lactations

Nineteen multiparous barren Holstein cows were subjected to an induction of lactation protocol for 21 d administering estradiol cypionate （2 mg kg-1 of body weight （BW） d-1, on day 1 to 14）, progesterone （0.10 mg kg-1 of BW, on day 1 to 7）, lfumethasone （0.03 mg kg-1 of BW, on day 18 to 20） and recombinant bovine somatotropin （rbST;500 mg per cow, on day 1, 6, 16 and 21）. At the end of lactation and with a minimum of a 2-mon dry period, the same cows were again hormonally induced into lactation. Cows in both lactations were not artiifcially inseminated, they were milked 3 times daily and received rbST throughout lactation. Mean accumulated milk yield at 305 d in milk （DIM） did not differ between the ifrst and second induced lactations （（9 710 ＆#177;1 728） vs. （9 309＆#177;2 150） kg;mean＆#177;SD）. Total milk yield （（12 707＆#177;3 406） vs. （12 306＆#177;4 218） kg;mean＆#177;SD） and lactation length （（405＆#177;100） vs. （410＆#177;91） d;mean＆#177;SD） were not different between the ifrst and second induced lactations. In a second study, 15 empirical models including exponential, power law, yield-density, sigmoidal and miscellaneous models were compared for their suitability by modeling 12-mon （n=334）, 18-mon （n=164） and 29-mon （n=22） lactation cycles of Holsteins cows induced into lactation and treated with rbST throughout the lactation. Hoerl （Y=ab1/xxc）, Wood （Y=axb exp（cx）） and Dhanoa （Y=ax（bc）exp（cx）） models were equally suitable to describe 12-mon lactations. An exponential model with ifve parameters （Y=exp（a＋bx＋cd2＋e/x）） showed the best ift for milk yield for 18-mon lactations. The rational model （Y=a＋bx/1＋cx＋dx2） was found to produce the closest ift for 29-mon lactations. It was concluded that, with the protocol used in the present study, multiparous cows respond favorably to a second cycle of induced lactation, with milk yield similar to that experienced during the ifrst cycle. Thus, dairy producers might be able to lengthen the productive life of infertile high producing cows with a renewal of artiifcial lactation, which would imply an overall reduction in voluntary culling of cows. Also, various equations used to describe the lactation curves demonstrated the potential for iftting monthly milk records of Holstein cows with prolonged lactations and induced hormonally into lactation.

Effects of Rumen Protected Methionine on Milk Yield and Milk Composition in Earlier Lactating Cow

A total of 12 mature healthy Holstein dairy cows of the nearly body weight （580±30） kg, milk yield （22.5±2.8） kg in the early stages of lactation were selected in this experiment. The cows were randomly divided into 2 groups, every group had 6 cows, every group had 6 repeats, and every repeat had 1 cow. Added 20 g protected methionine in earlier lactating cow food every day. The results showed that protected methionine increased milk yield by 10.83%, testing group milk yield was significantly different than that of control （P〈0.05）; protected methionine increased milk fat by 5.98%, testing group milk fat was significantly different than that of control （P〈0.05）; Milk protein increased by 2.15%, but bad insignificantly different （P〉0.05）; dry matter of milk had the tendency of decrease, but had insignificant difference （P〉0.05）.

Bacillus subtilis Co-transfected with a Lysine-rich and a Methionine-rich Protein Gene and Its Effect on Cow Milk Production

The probiotic Bacillus subtilis （B. subtilis） was widely applied in animal production as feed additive. Lysine （Lys） and methionine （Met） were the two most important limiting amino acids in livestock animal feed. Raising Lys and Met contents in B. subtilis would provide better effects for animal production and save Lys and Met supplements. We still didn＇t know whether Lys- rich and Met-rich protein genes from plants could be transfected into B. subtilis and expressed at a high level so as to improve animal production, such as milk production as an additional diet. The Lys-rich protein gene （Cflr） and Met-rich 10 ku-δ Zein were cloned from pepper anther and maize endosperm, respectively. Then they were constructed into plasmids individually and successfully cotransfected into B. subtilis. Upon IPTG induction, mRNAs and protein expressions could be observed. Lys and Met contents in the fermentation broth were raised by 65.92% and 46.39%, respectively. After feeding 200 g and 400 g· cow^-1· d^-1, transgenic B. subtilis fermentation broth, the milk yield, milk protein and milk fat contents all significantly increased. The Lys-rich protein gene （Cflr） and Met-rich 10 ku-δ Zein were successfully transfected into B. subtilis. Contents of Lys and Met in the transgenic B. subalis obviously raised and the fermentation broth of the transgenic bacteria could effectively improve milk yield and quality.

Study on the Milk Yield Pattern of Maiwa Yak

The change in lactation of Maiwa yak was studied based on the data of locating Maiwa yak in warm seasons during 2003- 2009. The results showed that the milk yield was increasing gradually during days 30- 70 after calving,reached the peak at days 70- 110,and decreased gradually to no milking whenafter. The milk yield of Maiwa yak was greatly influenced by lactation age rather than the yearly effect.

Effects of Chinese Herb Additive on Milk Yield and Anti-heat Stress Ability of Holstein Cows

[Objective] To explore the effects of Chinese herb additive on milk yield and anti-heat stress ability of Holstein diary cow. [Method] A total of 36 Holstein cows at same parity and with similar milk yield were randomly divided into three groups, namely, control group, Chinese medi- cine group I and Chinese medicine group I1. The cows in the Chinese medicine group I were fed basal diet containing 4% compound Chinese herb additive; those in the Chinese medicine group II were fed basal diet containing 3% compound Chinese herb additive; and those in the control group were fed common basal diet. All cows in the three groups were analyzed comparatively. [Result] Supplementing some compound Chinese herb ad- ditive into basal diet increased milk yield and anti-heat stress ability of Holstein cows, besides, it also decreased cow diseases like cow mastitis. The Chinese medicine group I generated the highest economic benefit of practical production. [ Conclusion] Supplementing Chinese herb additive in- to basal diet is an effective way to relieve heat stress and increase milk yield.

Effect of Pennisetum purpureum Schum cv. Guiminyin on Milk Yield and Quality of Jersey Cattle at Lactation Stage

The study aimed to research the forage value of Pennisetum purpureum Schum cv.Guiminyin in dairy industry and then provide scientific support for feeding jersey cattle with P.purpureum Schum cv.Guiminyin.Totally 20 jersey cattle at lactation stage were selected and divided into two groups randomly,10 cattle each group.The cattle were fed with P.purpureum Schum cv.Guiminyin and P.purpureum cv.Mott×（P.americanum×P.purureum）cv.Guimu No.1,respectively.The results showed that P.purpureum Schum cv.Guiminyin performed well in both nutritional value and palatability,and received remarkable effects on jersey cattle.The milk yield was 5.4%higher than that of before test,and the average daily milk yield was（11.65±0.07）kg/cattle.Compared with control group,milk fat percentage,lactoprotein content and overall milk-solid content were improved somewhat.Feeding jersey cattle with P.purpureum Schum cv.Guiminyin at lactation stage could increase their milk yield and milk quality.

A Study on the Correlation of Milk Yield of Cows with Seismicity and ULF Magnetic Field Variations

A statistical study on the basis of one-year data of 2014 has been performed in order to find whether abnormal animal behavior is related with seismic activity and also whether the ULF (Ultra Low Frequency) electromagnetic radiation might be a possible sensory mechanism of abnormal animal behavior. Abnormal animal behavior has been studied with the use of digitally recorded milk yield of cows at Ibaraki Prefecture Livestock Station, and the ULF magnetic field changes have been studied with the data at a magnetic observatory of Kakioka. As the result of correlation analyses, clear responses are observed for both the milk yield of cows and ULF magnetic field changes (both ULF radiation (ULF emissions from the lithosphere) and ULF depression (as an indicator of lower ionospheric perturbations)) for most powerful and not distant earthquakes (EQs) with magnitude > 6, that is, the milk yield of cows is found to exhibit a conspicuous depletion about 17 - 18 days before an EQ, though the correlation coefficient is not so big. Another important objective in this paper is to identify that ULF radiation is the main agent of abnormal behavior so that we have compared the temporal evolutions of milk yield of cows, ULF radiation and ULF depression for three major EQs. As a result, it is found that ULF radiation happens, at least, during the periods of abnormal depletion of milk yield of cows.

Effect of Bospro on High and Mid-to-Low Milk Yielding Chinese-Holstein Cow

A total of 90 cows from two farms (farm A 30 cows, farm B 60 cows) were used to study the effect of Bospro on milk production, milk quality and subclinical mastitis incidence. The cows in the test group were supplied with 20 g of Bospro per head per day and meanwhile, the percentage of milk fat, protein and lactose and moisture of the milk samples were analysed. The results showed that the milk yield of both high production and mid-to-low milk producting cows increased by 3.3% to 5.3% respectively compared with their control group of cows, but there was no changes on the milk content between the treated and the control cows. The treated cows also showed an increased body weight (P>0.05) and significantly reduced incidence of mastitis, as Compared with that of the control group.The experiment dcmonstrats that Bospro can increase milk yield, but not at the expense of milk quality and body weight.

Genomic patterns of homozygosity and inbreeding depression in MurcianoGranadina goats

Background:Inbreeding depression can adversely affect traits related to fitness,reproduction and productive performance.Although current research suggests that inbreeding levels are generally low in most goat breeds,the impact of inbreeding depression on phenotypes of economic interest has only been investigated in a few studies based on genealogical data.Results:We genotyped 1040 goats with the Goat SNP50 BeadChip.This information was used to estimate different molecular inbreeding coefficients and characterise runs of homozygosity and homozygosity patterns.We detected38 genomic regions with increased homozygosity as well as 8 ROH hotspots mapping to chromosomes 1,2,4,6,14,16 and 17.Eight hundred seventeen goats with available records for dairy traits were analysed to evaluate the potential consequences of inbreeding depression on milk phenotypes.Four regions on chromosomes 8 and 25were significantly associated with inbreeding depression for the natural logarithm of the somatic cell count.Notably,these regions contain several genes related with immunity,such as SYK,IL27,CCL19 and CCL21.Moreover,one region on chromosome 2 was significantly associated with inbreeding depression for milk yield.Conclusions:Although genomic inbreeding levels are low in Murciano-Granadina goats,significant evidence of inbreeding depression for the logarithm of the somatic cell count,a phenotype closely associated with udder health and milk yield,have been detected in this population.Minimising inbreeding would be expected to augment economic gain by increasing milk yield and reducing the incidence of mastitis,which is one of the main causes of dairy goat culling.

Effect of Zinc Methionine Supplementation on Productive Performance of Lactating Friesian Cows

Twelve lactating Friesian Cows with body weight of 450 to 550 kg and in the second to fifth lactating season were used after 8 weeks of cal- ving in a complete switch-back design. The cows were fed a basal ration of 35% concentrate feed mix-ture with 40% berseem and 25% rice straw （ on a dry matter （DM） basis） without supplementation （ G1 ） or supplemented with 5 and 10 g zinc methionine per head per day （G2 and G3, respectively）. Nutrient digestibility coefficients and nutritive values were significantly increased （P 〈0.05） by zinc methionine supplementation. Cows in G2 had the highest feed intake of total digestible nutrients （TDN） and digestible crude protein （DCP）, followed by Ga and G1, respectively （ P 〈 0.05 ）. The ruminal total volatile fatty acid concentration increased and ammonia nitrogen decreased significantly （ P 〈 0.05 ） by zinc methio-nine supplementation. Cows in G3 showed the highest plasma total protein, albumin, and globulin concen- trations （ P 〈 0.05 ）. Zinc methionine supplementa- tion led to significant decreases （ P 〈 0.05 ） in the activities of aspartate aminotransferase and alanine aminotransferase. A significant increase （ P 〈 0.05 ） was observed in the milk yield for G2 （2.54 kg/d or 18. 1% ） and G3 （ 1.95 kg/d or 14.2% ） compared with the control group. The corresponding increase in 4% fat-corrected milk （FCM） was 2.85 and 2.03 kg/d （21.63% and 15.74% ） for G2 and G3, respectively. Cows in G2 had the highest fat, total protein, and total solids contents, and the yield of all milk constitu- ents and animals in G3 showed the highest lactose, solids-not-fat, and ash contents. Zinc methionine sup- plementation improved feed conversion, reducing the quantities of DM, TDN, and DCP required to pro- duce 1 kg of 4% FCM （P〈0.05）. The average dai- ly feed cost per kilogram of 4% FCM decreased and the average income from milk production increased with zinc methionine supplementation （ P 〈 0.05 ）. Quadratic analysis showed that the optimal level of zinc methionine supplementation is 6 g per head per day in terms of milk yield and net revenue.

Impact of Quebracho Tannins Supplementation on Productive and Reproductive Efficiency of Dairy Cows

This study was conducted to investigate effects of supplementing two doses of quebracho tannins (QT;100 or 200 g/cow/d;QT100 or QT200) pre and post parturition to thirty Holstein dairy cows on Dry Matter Intake (DMI), milk yield and composition, blood metabolites and reproductive performance for 12 weeks. There were no significant changes in DMI due to QT at transition period of dairy cows. QT supplementation at either level decreased (P 0.05) the total number of ovarian follicles, number of large follicles, diameter of largest follicle, number of small follicles, number and diameter of corpus luteum, and progesterone concentration. The inclusion of QT increased days open and number of services per conception, which consequently decreased conception rate, compared to the control cows. QT100 decreased (P

A case study investigating the efects of emergency vaccination with Brucella abortus A19 vaccine on a dairy farm undergoing an abortion outbreak in China

Brucellosis is an important zoonosis that results in substantial economic losses to the livestock industry through abortions and reduced milk yield.This study investigated an abortion outbreak in a dairy herd and then explored the efects of emergency vaccination with Brucella abortus A19 vaccine on the incidence of abortion and milk yield.A full dose of vaccine(6×10^(10)—12×10^(10)colony forming units,CFU)was administered subcutaneously to calves and non-pregnant heifers,and a reduced dose(6×10^(8)—12×10^(8)CFU)to adult cows and pregnant replacement heifers.Rose Bengal Test was used to screen Brucella infection status and then positive samples were tested with a C-ELISA.Animals that tested positive for both tests were considered positive to Brucella spp.The animal-level seroprevalence of brucellosis was 23.1%(95%CI:17.0,30.2),and the attributable fraction of abortions in seropositive animals was 89.1%(95%CI:64.3,96.7).The odds of seropositivity were signifcantly higher in cows that aborted compared to cows that calved normally(OR=21.4,95%CI:4.4,168.4).Cows in sheds A2 and C1 were 10.2(95%CI:1.4,128.0)and 17.0(95%CI:2.8,190.3)times more likely to be seropositive than cows in shed B1.Antibodies were not detectable in most heifers 12 months post-vaccination.The efectiveness of the vaccine in preventing abortions was estimated to be 56.8%(95%CI:15.8,77.8)for the entire herd,but increased to 86.7%(95%CI:4.4,98.1)when only primiparous heifers were considered.Furthermore,a signifcant increase in the average herd 305-day milk yield one-year after vaccination was also observed relative to that in the previous three years.It is concluded that emergency vaccination of a dairy herd undergoing an abortion outbreak with the A19 vaccine efectively reduced the incidence of abortion and indirectly increased milk yield one-year after vaccination.

Physiological Studies on the Effect of Fenugreek on Productive Performance of White New-Zealand Rabbit Does

The objective of the current work is to investigate the possible beneficial effects of forced feeding of fenugreek to rabbit does on their milk composition, milk yield, anemia screening parameters, immunity and the growth performance of bunnies. Twenty white New Zealand female rabbits were randomly assigned into 5 groups: normal control and 4 treated groups (vehicle (molasses), fenugreek powdered seeds + molasses, sprouted fenugreek + molasses, and fenugreek oil + molasses). All treated groups took the given doses orally for two days before parturition and 13 days after parturition for 2 successive pregnancies. Blood samples were collected from each doe on the 13th day of lactation for determination of hematological, biochemical and immunological parameters. Milk samples were taken for evaluation of milk composition. All rabbit does and their bunnies were weighed for calculation of the milk yield. The fenugreek seeds and oil administered groups (G3 & G5) recorded the highest percent values of fat, protein, lactose, total solids and solid not fat contents of the rabbits’ milk in both 1st and 2nd lactation periods relative to other tested groups. At the beginning and mid of lactation periods, the milk yields recorded non-significant differences either between tested groups or between 1st and 2nd pregnancy in the same group. Whereas, at the end of lactation, germinated seeds (G4) and oil (G5) treated groups recorded significantly higher rates of milk yield relative to control and fenugreek seeds groups. Bunnies’ body weights suckling from dams of group III (G3) recorded the highest weights relative to other tested groups in both 1st and 2nd pregnancy. During the 1st lactation period, all experimental groups showed significant reduction of white blood cells, while, G3 and G4 recorded significant elevation during 2nd lactation period. Rabbits treated with fenugreek seeds powder (G3) showed a significant raise of phagocytic activity and phagocytic index. Fenugreek seeds group (G3) and germinated one (G4) showed significant red blood corpuscles and packed cell volume raise relative to other groups during both 1st and 2nd lactation periods.

Seasonal Variations and Its Impacts on Livestock Production Systems with a Special Reference to Dairy Animals:An Appraisal

Seasonal climatic variations is one of the most important environmental issues at present,the devastating impact of which is visualized on the ecology,ecosystem,and species survival.The livestock sector,which has been the source of animal protein for ever-increasing human masses,is subjected to the increased environmental temperature and higher frequency of extreme events.The impact of a high degree of heat stress is found to have a direct bearing on the milk production,growth,feed intake,reproductive efficiency,and disease incidence of the animals.The environmental temperature above the thermo-neutral zone of the animals has not only been adversely affecting the productivity and survival in the intensive livestock production systems,but the impact is equally seen in the extensive systems.Besides reduced milk production and change in composition,the impact of heat stress on dairy animals,in general,can be seen from the reduction of sperm quantity and quality in case of male and a marked decline in fertility and embryo quality in the case of females.The paper analyses varied aspects of climate change impacts on production,productivity,reproduction,and health of livestock,with a special focus on dairy animals.

On the Precursory Abnormal Animal Behavior and Electromagnetic Effects for the Kobe Earthquake (M~6) on April 12, 2013

After the 2011 Tohoku earthquake (EQ), there have been numerous aftershocks in the eastern and Pacific Ocean of Japan, but EQs are still rare in the western part of Japan. In this situation a relatively large (magnitude (M) ~6) EQ happened on April 12 (UT), 2013 at a place close to the former 1995 Kobe EQ (M~7), so we have tried to find whether there existed any precursors to this EQ, especially abnormal animal behavior (milk yield of cows), observed at Kagawa, Shikoku, near the EQ epicenter. The milk yield of cows has been continuously monitored at Kagawa, and it is found that the milk yield exhibited an abnormal depletion about 10 days before the EQ. This behavior has been extensively compared with the former electromagnetic precursors (ULF radiation, ionos-pheric perturbation). This leads to the discussion on the sensory mechanism of unusual behavior of mild yield of cows, and it may be suggested that ULF radiation among different electromagnetic precursors is a mostly likely driver, at least, for this EQ.

Influence of yeast on rumen fermentation,growth performance and quality of products in ruminants:A review

This review aims to give an overview of the efficacy of yeast supplementation on growth performance,rumen pH,rumen microbiota,and their relationship to meat and milk quality in ruminants.The practice of feeding high grain diets to ruminants in an effort to increase growth rate and weight gain usually results in excess deposition of saturated fatty acids in animal products and increased incidence of rumen acidosis.The supplementation of yeast at the right dose and viability level could counteract the acidotic effects of these high grain diets in the rumen and positively modify the fatty acid composition of animal products.Yeast exerts its actions by competing with lactate-producing(Streptococcus bovis and Lacto-bacillus)bacteria for available sugar and encouraging the growth of lactate-utilising bacteria(Mega-sphaera elsdenii).M.elsdenii is known to convert lactate into butyrate and propionate leading to a decrease in the accumulation of lactate thereby resulting in higher rumen pH.Interestingly,this creates a conducive environment for the proliferation of vaccenic acid-producing bacteria(Butyrivibrio fibrisolvens)and ciliate protozoa,both of which have been reported to increase the ruminal concentration of trans-11 and cis-9,trans-11-conjugated linoleic acid(CLA)at a pH range between 5.6 and 6.3.The addition of yeast into the diet of ruminants has also been reported to positively modify rumen biohydrogenation pathway to synthesise more of the beneficial biohydrogenation intermediates(trans-11 and cis-9,trans-11).This implies that more dietary sources of linoleic acid,linolenic acid,and oleic acid along with beneficial biohydrogenation intermediates(cis-9,trans-11-CLA,and trans-11)would escape complete bio-hydrogenation in the rumen to be absorbed into milk and meat.However,further studies are required to substantiate our claim.Therefore,techniques like transcriptomics should be employed to identify the mRNA transcript expression levels of genes like stearoyl-CoA desaturase,fatty acid synthase,and elon-gase of very long chain fatty acids 6 in the muscle.Different strains of yeast need to be tested at different doses and viability levels on the fatty acid profile of animal products as well as its vaccenic acid and rumenic acid composition.

Effect of exogenous fibrolytic enzymes on performance and blood profile in early and mid-lactation Holstein cows

The supplementation of exogenous fibrolytic enzymes(EFE) to dairy cows diets could be a strategy to improve fiber degradation in the rumen which is especially important for the early lactating cows characterized by a high milk energy output and an insufficient energy intake. The objective of this study was to examine the effects of a fibrolytic enzyme product(Roxazyme G2 Liquid, 3.8 and 3.9 mL/kg total mixed ration [TMR] DM) supplemented to a TMR on production performance and blood parameters of dairy cows during early(trial 1) and mid-lactation(trail 2). In addition, rumination activity was measured in trial 2. The nutrient digestibility of the experimental TMR was obtained by using wethers. In the digestibility trial, EFE was supplemented at a rate of 4.4 m L/kg Roxazyme G2 Liquid TMR-DM. The TMR contained 60% forage and 40% concentrate(DM basis). Twenty eight 50 ± 16 days in milk(DIM)and twenty six 136 ± 26 DIM Holstein cows were used in two 8-wk completely randomized trails,stratified by parity and milk yield level. One milliliter of the enzyme product contained primarily cellulase and xylanase activities(8,000 units endo-1,4-? glucanase, 18,000 units endo-1,3(4)-? glucanase and 26,000 units 1,4-? xylanase). No differences in digestibility of DM, OM, CP, NDF and ADF were observed(P >0.05) between the control and the EFE supplemented TMR. Addition of EFE to the TMR fed to early(trial 1) and mid-lactation cows(trial 2) did not affect daily dry matter intake(DMI), milk yield,4% fat-corrected milk, energy-corrected milk(ECM), concentration of milk fat, protein, fat-protein-quotients, somatic cell score, energy balance, and gross feed efficiency of early and mid-lactation cows(P >0.05). Mid-lactation cows(trial 2) fed with TMR enzyme showed a tendency of a slightly higher ECM yield(P = 0.09). The tested blood parameters were not affected by treatment in trials 1 and 2(P >0.05).Exogenous fibrolytic enzymes supplementation did not alter daily time spent ruminating in trial 2(P =0.44). In conclusion, under the conditions of this study, no positive effects of enzyme supplementation on dairy performance and health status of dairy cows during early and mid-lactation were observed.