Milk Yield In Dairy Cows Research Articles

Plasma estrone sulfate, clinical biochemistry, and milk yield of dairy cows carrying a fetus from a bull or its clone

The aim of this article was to compare plasma estrone sulfate (E1SO4), clinical biochemistry, and milk yield of dairy cows carrying a female fetus from a bull (BULL) or from its clone (CLONE), evaluating also the relationship between the former variables and the birth weight of the newborn. Sixteen recipient dairy Friesian heifers (10 BULL and 7 CLONE) received a female embryo, obtained by in vitro embryo production and sexing by polymerase chain reaction with the semen of the BULL or the CLONE. Blood samples on all cows were obtained before feed distribution in the morning from jugular vein from 4 weeks before to 4 weeks after calving, to be analyzed for metabolic profile. The samples from late gestation were also analyzed for E1SO4 concentration. To separately assess the effect of calf birth weight (CBW), data were categorized as follows: low (<39 kg; BWT-A), mid (39–46 kg; BWT-B), and high (>46 kg; BWT-C). The plasma concentrations of β-hydroxybutyric acid (BHB, P = 0.019), Na (P = 0.002), Cl (P = 0.026), strong cation–anion balance (P = 0.020), total bilirubin (P = 0.054), and α1-globulin (P = 0.044) were higher in prepartum BULL recipients than those in CLONE, whereas BHB (P = 0.021) and Mg (P = 0.090) were higher in postpartum BULL recipients, while no differences were recorded in the remaining postpartum parameters. The CBW class had significant interaction with week of gestation on antepartum plasma estrone sulfate (P = 0.021), whereas CBW per se affected antepartum plasma BHB (P = 0.021), and nonesterified fatty acids (NEFA; P = 0.011) being higher in BWT-C which also had the lower NEFA concentration during postpartum. Milk yield was unaffected by the sire used, both for quantitative and qualitative aspects. Cows carrying heavier fetus (BWT-C) had a different lactation affected by month compared with the other 2 CBW groups. From these results, there were no differences between BULL and CLONE recipients. Estrone sulfate, BHB, and NEFA may be used to predict CBW and provide different nutritional management during gestation.

The effect of routine hoof trimming on locomotion score, ruminating time, activity, and milk yield of dairy cows

The objective of this study was to quantify the effect of hoof trimming on cow behavior (ruminating time, activity, and locomotion score) and performance (milk yield) over time. Data were gathered from a commercial dairy farm in Israel where routine hoof trimming is done by a trained hoof trimmer twice per year on the entire herd. In total, 288 cows spread over 6 groups with varying production levels were used for the analysis. Cow behavior was measured continuously with a commercial neck activity logger and a ruminating time logger (HR-Tag, SCR Engineers Ltd., Netanya, Israel). Milk yield was recorded during each milking session with a commercial milk flow sensor (Free Flow, SCR Engineers Ltd.). A trained observer assigned on the spot 5-point locomotion scores during 19 nighttime milking occasions between 22 October 2012 and 4 February 2013. Behavioral and performance data were gathered from 1wk before hoof trimming until 1wk after hoof trimming. A generalized linear mixed model was used to statistically test all main and interactive effects of hoof trimming, parity, lactation stage, and hoof lesion presence on ruminating time, neck activity, milk yield, and locomotion score. The results on locomotion scores show that the proportional distribution of cows in the different locomotion score classes changes significantly after trimming. The proportion of cows with a locomotion score ≥3 increases from 14% before to 34% directly after the hoof trimming. Two months after the trimming, the number of cows with a locomotion score ≥3 reduced to 20%, which was still higher than the baseline values 2wk before the trimming. The neck activity level was significantly reduced 1d after trimming (380±6 bits/d) compared with before trimming (389±6 bits/d). Each one-unit increase in locomotion score reduced cow activity level by 4.488 bits/d. The effect of hoof trimming on ruminating time was affected by an interaction effect with parity. The effect of hoof trimming on locomotion scores was affected by an interaction effect with lactation stage and tended to be affected by interaction effects with hoof lesion presence, indicating that cows with a lesion reacted different to the trimming than cows without a lesion did. The results show that the routine hoof trimming affected dairy cow behavior and performance in this farm.

Nutritive value of maize silage in relation to dairy cow performance and milk quality.

Maize silage has become the major forage component in the ration of dairy cows over the last few decades. This review provides information on the mean content and variability in chemical composition, fatty acid (FA) profile and ensiling quality of maize silages, and discusses the major factors which cause these variations. In addition, the effect of the broad range in chemical composition of maize silages on the total tract digestibility of dietary nutrients, milk production and milk composition of dairy cows is quantified and discussed. Finally, the optimum inclusion level of maize silage in the ration of dairy cows for milk production and composition is reviewed. The data showed that the nutritive value of maize silages is highly variable and that most of this variation is caused by large differences in maturity at harvest. Maize silages ensiled at a very early stage (dry matter (DM) < 250 g kg(-1)) were particularly low in starch content and starch/neutral detergent fibre (NDF) ratio, and resulted in a lower DM intake (DMI), milk yield and milk protein content. The DMI, milk yield and milk protein content increased with advancing maturity, reaching an optimum level for maize silages ensiled at DM contents of 300-350 g kg(-1), and then declined slightly at further maturity beyond 350 g kg(-1). The increases in milk (R(2) = 0.599) and protein (R(2) = 0.605) yields with maturity of maize silages were positively related to the increase in starch/NDF ratio of the maize silages. On average, the inclusion of maize silage in grass silage-based diets improved the forage DMI by 2 kg d(-1), milk yield by 1.9 kg d(-1) and milk protein content by 1.2 g kg(-1). Further comparisons showed that, in terms of milk and milk constituent yields, the optimum grass/maize silage ratio depends on the quality of both the grass and maize silages. Replacement of grass silage with maize silage in the ration, as well as an increasing maturity of the maize silages, altered the milk FA profile of the dairy cows, notably, the concentration of the cis-unsaturated FAs, C18:3n-3 and n-3/n-6 ratio decreased in milk fat. Despite variation in nutritive value, maize silage is rich in metabolizable energy and supports higher DMI and milk yield. Harvesting maize silages at a DM content between 300 and 350 g kg(-1) and feeding in combination with grass silage results in a higher milk yield of dairy cows.

Association between somatic cell count during the first lactation and the cumulative milk yield of cows in Irish dairy herds

Reduced potential milk yield is an important component of mastitis costs in dairy cows. The first aim of this study was to assess associations between somatic cell count (SCC) during the first lactation, and cumulative milk yield over the first lactation and subsequent lifetime of cows in Irish dairy herds. The second aim was to assess the association between SCC at 5 to 30d in milk during parity 1 (SCC1), and SCC over the entire first lactation for cows in Irish dairy herds. The data set studied included records from 51,483 cows in 5,900 herds. Somatic cell count throughout the first lactation was summarized using the geometric mean and variance of SCC. Data were analyzed using linear models that included random effects to account for the lack of independence between observations, and herd-level variation in coefficients. Models were developed in a Bayesian framework and parameters were estimated from 10,000 Markov chain Monte Carlo simulations. The final models were a good fit to the data. A 1-unit increase in mean natural logarithm SCC over the first lactation was associated with a median decrease in first lactation and lifetime milk yield of 135 and 1,663kg, respectively. A 1-unit increase in the variance of natural logarithm SCC over the first lactation was associated with a median decrease in lifetime milk yield of 719kg. To demonstrate the context of lifetime milk yield results, microsimulation was used to model the trajectory of individual cows and evaluate the expected outcomes for particular changes in herd-level geometric mean SCC over the first lactation. A 75% certainty of savings of at least €199/heifer in the herd was detected if herd-level geometric mean SCC over the first lactation was reduced from ≥120,000 to ≤72,000cells/mL. The association between SCC1 and SCC over the remainder of the first lactation was highly herd dependent, indicating that control measures for heifer mastitis should be preferentially targeted on an individual-herd basis toward either the pre- and peripartum period, or the lactating period, to optimize the lifetime milk yield of dairy cows.

Effect of low light intensity at night on cow traffic in automatic milking systems

Several studies have shown benefits of long-day (16 h) photoperiod in lactating dairy cows, but have not identified a suitable light intensity for the dark hours. It is known that the locomotion pattern of dairy cows is altered at low light intensities and this may translate to reduced cow traffic and milking frequency, which would have a negative impact on system productivity. However, it is also recognised that a significant disturbance of rest may have a negative impact on the health and productivity of high-yielding dairy cows. This study examined the effect of three different night-time light intensities (LOW: 11 ± 3, MED: 33 ± 1 and HIGH: 74 ± 6 lx) on number of gate passages, milking frequency and milk yield in dairy cows in automatic milking systems. The study was conducted in Sweden during the winter of 2012–13 and the treatments were applied in a crossover design to three herds with an automatic milking system. Minimum day time light intensity was 158 lx. Data on gate passages, milking frequency and milk yield for 172 ± 49 (mean ± s.d.) cows during the last 22 days of each 34-day study period were analysed for treatment differences and differences in daily distribution over 24 h, during day time and night time. Light intensity did not affect total number of gate passages per 24-h period and cow, but number of gate passages per hour and cow was in all treatments lower during night time than during day time. Milking frequency was increased in MED compared with both HIGH and LOW (P &lt; 0.05). Milk yield decreased with reduced light intensity, and differed significantly between HIGH and LOW treatments, 45 ± 1 kg and 44 ± 1 kg, respectively (P &lt; 0.001). Our conclusion is that reducing light intensity to 11 lx at night time does not affect cows’ general activity as gate passages remained the same for all treatments. However, milk yield decreased with reduced light intensity, which might be related to a lower feed intake. We argue that providing night light for dairy cows, as required by many welfare acts, might be related to production level rather than welfare aspects and that the recommendations should be revised.

Galactopoietic Activity of Dibutyl Phthalate Isolated from Vaccaria segetalis

A galactopoietic compound, identified as dibutyl phthalate (DBP), was isolated from Vaccaria segetalis. The activity of DBP on lactation ability of dairy cow mammary gland epithelial cells (DCMECs) cultured in vitro and dairy cow was evaluated. Results showed that DBP could promote cell viability, proliferation ability, lactose and β-casein secretion of DCMECs, which could also raise the milk yields of dairy cows significantly.

Effect of relocation and sire lineage on behaviour and milk yield of dairy cows

Abstract. The objective of the present study was to analyse the maintenance behaviour of cows after shift from tie-stall barn to free-stall barn. The activities were analysed in relation to the time of moving of the cows. Forty-one Holstein cows were used. Cows were observed for three 24-h (first, second and tenth day) periods after moving into the new barn with free-stall housing. The shortest times of lying and ruminating were recorded at the first day after relocation (336.3 min, 628.0 min, 756.1 min, P&lt;0.001; 318.0 min, 325.0 min, 440.5 min, P&lt;0.001). The longest time was recorded for the duration of standing (1 103.7 min, 811.9 min, 683.9 min, P&lt;0.001). The period’s number of lying and ruminating were the lowest at the first day and highest at the tenth day after relocation (7.34, 14.07, 16.34, 14.32, 15.75, 18.58, P&lt;0.001). The opposite trend was found in the period’s number of feeding and standing (17.46, 12.73, 9.54 and 24.93, 18.19 and 12.41; P&lt;0.001). Sires progeny was significantly manifested in times of total lying, standing (P&lt;0.05) and feeding (P&lt;0.01) as well as in the number of lying periods (P&lt;0.05). Cows produced significantly less milk at the first day after removing than the last day before (23.76 kg vs. 30.97 kg, P&lt;0.001). Milk yield returned towards basal levels at the 13th day (31.82 kg). Milk production was different among sires.

Randomized clinical field trial on the effects of butaphosphancyanocobalamin and propylene glycol on ketosis resolution and milk production in dairy cows

Ketosis, generally measured as increased concentrations of beta-hydroxybutyrate (BHBA) in the blood, is common in dairy cattle and caused by a period of negative energy balance that is nearly ubiquitous at the beginning of lactation. The consequences of ketosis include increased risk of other diseases and decreased production and reproductive performance. Propylene glycol (PG) has been recommended for treatment of ketosis because of its role in gluconeogenesis, and has recently been shown to be effective for the treatment of subclinical ketosis in a large-scale clinical field trial. It has been hypothesized that administration of vitamin B12 (cyanocobalamin) may increase gluconeogenesis by increasing the activity of methylmalonyl-CoA mutase, a vitamin B12-dependent enzyme and important component of the tricarboxylic acid (TCA) cycle. Results of a recent study conducted on 1 herd suggested that a combination of butaphosphan-cyanocobalamin (B+C; Catosal®, Bayer Animal Health) was efficacious for the treatment of cows with ketosis. The purpose of this study was to determine the effects of B+C and the duration of PG treatment (3 vs 5 days) on ketosis resolution and early lactation milk yield in dairy cows.

Association between somatic cell count after first parturition and cumulative milk yield in dairy cows

The aim was to assess the association between the somatic cell count of parity 1 cows between 5 and 30 days in milk (SCC1), and subsequent cumulative milk yield over...

Technical note: A mathematical function to predict daily milk yield of dairy cows in relation to the interval between milkings

The milk production of a dairy cow is characterized by lactation production, which is calculated from daily milk yields (DMY) during lactation. The DMY is calculated from one or more milkings a day collected at the farm. Various milking systems are in use today, resulting in one or many recorded milk yields a day, from which different calculations are used to determine DMY. The primary objective of this study was to develop a mathematical function that described milk production of a dairy cow in relation to the interval between 2 milkings. The function was partly based on the biology of the milk production process. This function, called the 3K-function, was able to predict milk production over an interval of 12h, so DMY was twice this estimate. No external information is needed to incorporate this function in methods to predict DMY. Application of the function on data from different milking systems showed a good fit. This function could be a universal tool to predict DMY for a variety of milking systems, and it seems especially useful for data from robotic milking systems. Further study is needed to evaluate the function under a wide range of circumstances, and to see how it can be incorporated in existing milk recording systems. A secondary objective of using the 3K-function was to compare how much DMY based on different milking systems differed from that based on a twice-a-day milking. Differences were consistent with findings in the literature.

DIAGNOSTIC STUDY OF EHRLICHIOSIS IN CATTLE OF MOSUL-IRAQ

Ehrlichiosis (Ehrlichia spp.) was detected in 132(70 Iranian,32 Turkish and 30 local breed)calves (10-14 months old) and 18 dairy cows of local breed (3-5 years old). Animals were brought to Veterinary Teaching Hospital, College of Veterinary Medicine, University of Mosul –Iraq from different farms of Mosul city-Iraq, with clinical signs of fever(40-41C 0 ),anorexia ,emaciation, decrease of milk yield in dairy cows ,paleness of mucous membrane, lymph node enlargement and ticks were detected on different body regions .All blood and buffy coat smears of calves were positive for morula like structures inside the cytoplasm of neutrophils , lymphocytes and monocytes when staining by Giemsa and Wright stains. For all animals , the appearance of Ehrlichia spp. Organisms in leukocytes coincided with erythropenia, leukopenia, and thrombocytopenia and a decrease in hematocrit and hemoglobin concentration. For eighteen dairy cows, Ehrlichia spp. organisms were identified in leukocytes of blood and milk samples. This is apparently the first evidence for Ehrlichia spp. infection in cattle in Iraq. In conclusion, the present study documents that Ehrlichia infection exists in Mosul-Iraq and indicates that the bacterium has been present but unnoticed in the area .Further investigation will be needed in order to characterize different species of Ehrlichia infection in cattle, and explain the role of vector and imported animals in introduction of the disease to our country.

Comparison of 2 systems of pasture allocation on milking intervals and total daily milk yield of dairy cows in a pasture-based automatic milking system

Cows milked in pasture-based automatic milking systems (AMS) have greater milking intervals than cows milked in indoor AMS. Long milking intervals greater than 16h have a negative effect on milk yield and udder health. The impact of 2 systems of pasture allocation in AMS on milking interval and yield was investigated at the FutureDairy AMS research farm (Elizabeth Macarthur Agricultural Institute, New South Wales Department of Primary Industries, Camden, New South Wales, Australia) in late November to early December 2010. Two- (2WG) versus 3-way grazing (3WG) allocations per 24-h period were compared in a field study to test the hypothesis that an increase in the frequency of pasture allocation would reduce the milking interval and, therefore, increase milking frequency. The study involved the entire milking herd of 145 cows, with (mean ± SD) DIM=121±90d, 7-d average milking frequency=1.52±0.41 milkings/cow per day, and 7-d average milk yield=21.3±7.6kg/cow per day. Cows were milked using 2 DeLaval VMS milking units (DeLaval International AB, Tumba, Sweden). Cows in the 3WG treatment had 31% reduced milking interval, 40% greater milking frequency, and 20% greater daily milk production compared with 2WG. Increased milking frequency and milk production for 3WG was associated with greater utililization levels of the AMS milking units throughout the day. These results support the recommendation that, wherever possible, farmers installing AMS should incorporate sufficient infrastructure to accommodate 3WG, which provides additional flexibility with managing extremely long (and short) milking intervals.

Production and utilization of ensiled forages by beef cattle, dairy cows, pregnant ewes and finishing lambs - A review

This paper reviews the production of, and factors affecting the performance of dairy cows, beef cattle and sheep offered silage based diets in Ireland and UK. Digestibility is the most important factor influencing the feed value of grass silage and consequently animal performance. Each 10 g kg-1 increase in digestive organic matter in the dry matter (DOMD) increases milk yield of dairy cows by 0.33 kg d-1, carcass gain of beef cattle by 23.8 g d-1 , carcass gain of finishing lambs by 9.3 g d-1, lamb birth weight by 52.3 g and ewe weight post lambing by 1.3 kg, respectively. Factors influencing feed value of grass silage are discussed including harvest date, wilting, fertilizer management, chop length and use of additives at ensiling. Maize silage increases the performance of cattle and sheep whilst whole crop wheat silage has no beneficial effect. Advances in silage technology, has enabled the ensiling high protein forages, such as red clover, lucerne and kale.

Effect Of Drying- Off Period And Teat Dipping On Productivity Of Dairy Cows

This study was conducted to investigate effect of period of drying off and teat dipping on dairy cow production. This study was carried out at Sami Asaad Dairy Farm at Abo-Hamad city in SharkiaProvince in the period from first of December, 2010 till end of November, 2011. The data were obtained from farm book record and were collected from one hundred dairy cows (Holstein Friesian) to assess the effect of length of dry off period, age and lactation season on dairy cow production. The obtained results showed that the cows with a dry period of 45, 46 and 59 days, had the highest milk yield at 305-day. So, increasing the dry period lead to an increase in milk yield of subsequent lactation. Furthermore, the total milk production was increased gradually from 3 to 7 years, after that it decreased. Also to evaluate the effect of teat dipping on dairy cow’s milk production in the period from first of July till end of September, 2011; the data obtained from sixteen dairy cows (Holstein Frisian), divided into 2 groups, group A (n= 8) wherethe udder washed, dried with a clean toilet tissues and the teats dipped in 70% ethyl alcohol solution, while group B (n=8) without teat dipping. The results revealed that the teat dipping after milking decrease the incidence of mastitis and increase milk yield. In conclusion, length of dry off period, age, lactation season and teat dipping have significantly effect on milk yield in dairy cows.

Association between digital dermatitis lesions and test-day milk yield of Holstein cows from 41 French dairy farms

The objective of this study was to estimate the association between digital dermatitis (DD) lesions and test-day milk yield (TDY) in dairy cows, taking into account the severity of the lesions. Data were collected for 6 mo on 47 French dairy farms endemically affected by DD and involved in a clinical trial aiming to assess the effectiveness of collective treatments against DD. The hind feet of all lactating cows were scored for DD by 14 trained investigators on a monthly basis using a 4-point M-stage scoring system (M0 to M4, M standing for Mortellaro). The DD status was defined in 3 categories at the animal level: no DD [scores of M0 and (or) M4 on both feet], moderate case (score of M1 on 1 or both feet and no M2 score), and severe case (score of M2 on 1 or both feet). All monthly TDY in the lactation were collected. The final complete data set included 7,599 TDY of 1,782 Holstein cows from 41 herds. The effect of DD lesions on the following TDY (i.e., within 30d after detection of a DD lesion) was analyzed separately for primiparous and multiparous cows, using mixed-models ANOVA, with TDY as repeated measures. During the trial, 38% of the primiparous and 41% of the multiparous cows were observed at least once with a DD lesion (moderate or severe case), the cows being observed with a DD lesion, on average, for 2 consecutive visits. Milk yield decreased significantly for cows diagnosed with a DD lesion. Primiparous cows produced, on average, 0.63kg/d less when DD was moderate and 0.50kg/d less when the disease was severe, compared with unaffected cows. Multiparous cows produced, on average, 0.50kg/d less when DD was moderate and 0.75kg/d less when the disease was severe, compared with unaffected cows. These results confirm that DD lesions have a significant effect on the milk yield of dairy cows, including when animals are rigorously treated. Milk yield losses, thus, should be considered when evaluating the costs and benefits of DD control programs.

Sütçü İneklerde Sarkoptik Uyuza Bağlı Meme Dermatitisinin Süt Verimi Üzerine Etkileri

Sütçü İneklerde Sarkoptik Uyuza Bağlı Meme Dermatitisinin Süt Verimi Üzerine Etkileri

Do mats matter? – Comparison of fertility traits and milk yield in dairy cows on rubber or concrete flooring

Abstract. Rubber flooring in dairy cows has been discussed controversially, because different studies found as well advantages as disadvantages regarding claw health. Until today little is known regarding the effect of rubber flooring on the reproductive performance of dairy cows. Therefore, the study aimed at comparing fertility and the milk yield of dairy cows on concrete or rubber flooring. Days to first breeding (DFB), days open (DO), services per conception (SC), heat detection rate (HDR), conception rate (first service; CR1st service) and the corresponding 100 days in milk (DIM) milk yield were evaluated for 139 lactation periods of 91 cows of the University Munich Livestock Center dairy herd. The cows entered the study as heifers and were housed on the same flooring system during their whole productive life. All cows underwent the same management, feeding, and climatic conditions. A mixed model procedure was used to analyse data. Cows on rubber (RSF) compared with cows on concrete flooring (CSF) showed less DFB (76.8/94.6; P&lt;0.01), less DO (98.8/138.4; P&lt;0.01), and no difference regarding SC (1.5/1.7; P=0.267). Furthermore, no differences regarding the 100 DIM milk yield could be established. The calculation of HDR (54.9%/27.9%) and CR1st service (39.4/29.4) showed also high advantages for the rubber flooring. It was concluded that rubber flooring affects an earlier onset of regular oestrus behaviour and improves the economically sensible fertility trait of calving interval by earlier pregnancy and less days open but does not cause higher milk yield.

Randomized clinical trial to compare the efficacy of two different antimicrobials on cure, milk production, and reproductive performance of dairy cows diagnosed with metritis

Two systemic antimicrobials are currently labeled in the United States for the treatment of metritis, ceftiofur and oxtetracycline. However, veterinarians may choose an alternative to ceftiofur, a third generation cephalosporin, because of concerns about the potential development of antimicrobial resistance. Ampicillin sodium is often used in an extra-label manner in the field to treat metritis in dairy cows, but there is little work published to support its use for this purpose. The objective of this study was to compare the efficacy of two antimicrobial treatments (ceftiofur hydrochloride versus ampicillin sodium) for resolution of clinical signs, reproductive performance, culling, and milk yield in dairy cows diagnosed with acute puerperal metritis.

Effects of metabolizable protein supply and amino acid supplementation on nitrogen utilization, milk production, and ammonia emissions from manure in dairy cows

Two experiments were conducted with the objective of investigating the effects of rumen-protected methionine (RPMet) supplementation of metabolizable protein (MP)-deficient or MP-adequate but Met-deficient diets on dairy cow performance. Experiment (Exp.) 1 utilized 36 Holstein dairy cows blocked in 12 blocks of 3 cows each. Cows within block were assigned to one of the following dietary treatments: (1) MP-adequate diet [AMP; positive MP balance according to the National Research Council (2001) dairy model]; (2) an MP-deficient diet supplemented with 100g of rumen-protected Lys (RPLys)/cow per day (DMPL); and (3) DMPL supplemented with 24g of RPMet/cow per day (DMPLM). Experiment 2 utilized 120 Holstein cows assigned to 6 pens of 20 cows each. Pens (3 per treatment) were assigned to one of the following dietary treatments: (1) AMP diet supplemented with 76g of RPLys/cow per day (AMPL); and (2) AMPL (74g of RPLys/cow per day) supplemented with 24g of RPMet/cow per day (AMPLM). Each experiment lasted for 10wk (2-wk adaptation and 8-wk experimental periods) following a 2-wk covariate period (i.e., a total of 12wk). In Exp. 1, the MP-deficient diets decreased apparent total-tract nutrient digestibility but had no statistical effect on dry matter intake (DMI), milk yield, or milk fat percentage and yield. Compared with AMP, DMPL decreased milk protein content; both DMPL and DMPLM diets decreased milk protein yield. Urinary N losses and milk urea-N concentration were decreased by the MP-deficient diets compared with AMP. The ammonia emitting potential of manure from the MP-deficient diets was decreased by about 37% compared with that of AMP manure. Plasma Lys and Met concentrations were not affected by treatment, but concentrations of His, Thr, and Val were lower for the MP-deficient diets compared with AMP. In Exp. 2, the AMPLM diet had lower milk yield than AMPL due to numerically lower DMI; no other effects were observed in Exp. 2. In conclusion, feeding MP-deficient diets supplemented with RPLys and RPMet did not statistically decrease milk yield in dairy cows in Exp. 1. However, without RPMet supplementation, milk protein content was decreased compared with the MP-adequate diet. Other amino acids, possibly His, may limit milk production in MP-deficient, corn or corn silage-based diets. A summary of 97 individual cow data from trials in which MP-deficient diets were fed suggested the National Research Council (2001) model under-predicts milk yield in cows fed MP-deficient diets (MP balance of –20 to –666g/d) in a linear manner: milk yield under-prediction [National Research Council (2001) MP-allowable milk yield, kg/d – actual milk yield, kg/d] = 0.0991 (±0.0905) + 0.0230 (±0.0003) × MP balance, g/d (R2=0.99).

Rumen-protected lysine, methionine, and histidine increase milk protein yield in dairy cows fed a metabolizable protein-deficient diet

The objective of this experiment was to evaluate the effect of supplementing a metabolizable protein (MP)-deficient diet with rumen-protected (RP) Lys, Met, and specifically His on dairy cow performance. The experiment was conducted for 12wk with 48Holstein cows. Following a 2-wk covariate period, cows were blocked by DIM and milk yield and randomly assigned to 1 of 4 diets, based on corn silage and alfalfa haylage: control, MP-adequate diet (ADMP; MP balance: +9 g/d); MP-deficient diet (DMP; MP balance: −317g/d); DMP supplemented with RPLys (AminoShure-L, Balchem Corp., New Hampton, NY) and RPMet (Mepron; Evonik Industries AG, Hanau, Germany; DMPLM); and DMPLM supplemented with an experimental RPHis preparation (DMPLMH). The analyzed crude protein content of the ADMP and DMP diets was 15.7 and 13.5 to 13.6%, respectively. The apparent total-tract digestibility of all measured nutrients, plasma urea-N, and urinary N excretion were decreased by the DMP diets compared with ADMP. Milk N secretion as a proportion of N intake was greater for the DMP diets compared with ADMP. Compared with ADMP, dry matter intake (DMI) tended to be lower for DMP, but was similar for DMPLM and DMPLMH (24.5, 23.0, 23.7, and 24.3kg/d, respectively). Milk yield was decreased by DMP (35.2kg/d), but was similar to ADMP (38.8kg/d) for DMPLM and DMPLMH (36.9 and 38.5kg/d, respectively), paralleling the trend in DMI. The National Research Council 2001model underpredicted milk yield of the DMP cows by an average (±SE) of 10.3±0.75kg/d. Milk fat and true protein content did not differ among treatments, but milk protein yield was increased by DMPLM and DMPLMH compared with DMP and was not different from ADMP. Plasma essential amino acids (AA), Lys, and His were lower for DMP compared with ADMP. Supplementation of the DMP diets with RP AA increased plasma Lys, Met, and His. In conclusion, MP deficiency, approximately 15% below the National Research Council requirements from 2001, decreased DMI and milk yield in dairy cows. Supplementation of the MP-deficient diet with RPLys and RPMet diminished the difference in DMI and milk yield compared with ADMP and additional supplementation with RPHis eliminated it. As total-tract fiber digestibility was decreased with the DMP diets, but DMI tended to increase with RP AA supplementation, we propose that, similar to monogastric species, AA play a role in DMI regulation in dairy cows. Our data implicate His as a limiting AA in high-producing dairy cows fed corn silage- and alfalfa haylage-based diets, deficient in MP. The MP-deficient diets clearly increased milk N efficiency and decreased dramatically urinary N losses.