Milk Weight Research Articles

Energy balance of individual cows can be estimated in real-time on farm using frequent liveweight measures even in the absence of body condition score

Existing methods for estimating individual dairy cow energy balance typically either need information on feed intake, that is, the traditional input–output method, or frequent measurements of BW and body condition score (BCS), that is, the body reserve changes method (EBbody). The EBbody method holds the advantage of not requiring measurements of feed intake, which are difficult to obtain in practice. The present study aimed first to investigate whether the EBbody method can be simplified by basing EBbody on BW measurements alone, that is, removing the need for BCS measurements, and second to adapt the EBbody method for real-time use, thus turning it into a true on-farm tool. Data came from 77 cows (primiparous or multiparous, Danish Holstein, Red or Jersey) that took part in an experiment subjecting them to a planned change in concentrate intake during milking. BW was measured automatically during each milking and real-time smoothed using asymmetric double-exponential weighting and corrected for the weight of milk produced, gutfill and the growing conceptus. BCS assessed visually with 2-week intervals was also smoothed. EBbody was calculated from BW changes only, and in conjunction with BCS changes. A comparison of the increase in empty body weight (EBW) estimated from EBbody with EBW measured over the first 240 days in milk (DIM) for the mature cows showed that EBbody was robust to changes in the BCS coefficients, allowing functions for standard body protein change relative to DIM to be developed for breeds and parities. These standard body protein change functions allow EBbody to be estimated from frequent BW measurements alone, that is, in the absence of BCS measurements. Differences in EBbody levels before and after changes in concentrate intake were calculated to test the real-time functionality of the EBbody method. Results showed that significant EBbody increases could be detected 10 days after a 0.2 kg/day increase in concentrate intake. In conclusion, a real-time method for deriving EBbody from frequent BW measures either alone or in conjunction with BCS measures has been developed. This extends the applicability of the EBbody method, because real-time measures can be used for decision support and early intervention.

Parlor performance basics

Several factors, including the number of milkers and desired milk quality, interact to determine parlor efficiency. One of the most important efficiency factors is maximizing total pounds of milk produced. The best method to evaluate this is to calculate milk production based as a per stall, per hour of operation number. This number can be calculated in any parlor or stall barn system, whether or not meters or milk-monitoring devices are installed. The information needed is the time in hours and tenths of an hour, the total amount of milk produced during the milking, and the number of units. The calculation is made by dividing the total milk produced by the number of milking units, and the resulting milk weight is then divided by the total time. On many dairies, total cows milked per day or per hour is commonly used as a proxy for pounds of milk output, but too often is used as the only measure. When cows are not prepped properly, throughput can increase even though less milk is produced! This is not the desired goal for any herd.

The use of individual diet modelling to optimise individual food choices. A focus on dairy products

The aim of this study was to apply individual diet modelling to analyse qualitative and quantitative changes in dairy products consumption, needed to achieve nutritional recommendations in an adult population. An individual isocaloric modelled diet was designed by linear programming to meet the French nutrient recommendations while deviating the least from the observed diet (dietary survey INCA 1, n = 1171). Variations in weight, energy and nutrients in observed and modelled diets were calculated for each food group ( n = 7), with a focus on dairy products. The results indicated that the weight of 3 food groups significantly increased in the modelled diet: starchy foods (+37%), fruit & vegetables (+62%) and dairy products (+19%). Within the dairy category, there was an increase (in weight) of fresh dairy products (+60%) and milk (+17%), a decrease of cheese (−48%), without significant change of dairy desserts. In the modelled diet, the contribution of dairy products to the total decrease in SFA and sodium was exclusively due to a decrease in cheese. Interestingly, the dairy products did not contribute to the decrease in added sugars. In conclusion, linear programming allows estimating the contribution of the different food groups and subgroups in nutritionally adequate and socially acceptable diet. In this French population, increasing the intake of the lowest energy-dense dairy products (i.e. fresh dairy products and milk) would be recommended. In the future, this new approach could help to revise or precise existing food-based dietary guidelines.

Brown midrib corn silage fed during the peripartal period increased intake and resulted in a persistent increase in milk solids yield of Holstein cows

The objective of this study was to evaluate transition cow performance when brown midrib corn silage (BMRCS; Mycogen F2F444) was included in the diet during the transition period, and to determine if any production response occurring during the first 3wk of lactation would persist from wk 4 to 15 when a common diet was fed. Seventy Holstein dairy cows were blocked by parity (either second or third and greater) and calving date and randomly assigned to the CCS (a mixture of varieties of conventional corn silage) or BMRCS treatment. Diets were formulated with the objective of keeping all ration parameters the same, with the exception of neutral detergent fiber digestibility. Neutral detergent fiber digestibility values (30 h) for CCS and BMRCS averaged 56.8 and 73.8%, respectively. Prepartum rations contained 47% corn silage, 18% wheat straw, 7% alfalfa haylage, and 28% concentrate, and averaged 45% neutral detergent fiber (DM basis). Postpartum rations contained 40% corn silage, 15% alfalfa haylage, 1% straw, and 44% concentrate. Milk weights (3×/d) and dry matter intake were recorded daily, and milk composition was measured weekly. Cows fed BMRCS had higher dry matter intake during the 2-wk period before calving (14.3 vs. 13.2kg/d) and the 3-wk period after calving (20.1 vs. 18.1kg/d) than did cows fed CCS. Yields of milk, solids, and lactose were increased, whereas a trend was observed for a reduction in somatic cell counts and linear scores in the postpartum period for cows receiving BMRCS during the transition. A significant carryover effect of BMRCS was observed on production from wk 4 to 15 when the common diet was fed, with yields of protein (1.36 vs. 1.30kg/d), lactose (2.24 vs. 2.12kg/d), and solids (5.82 vs. 5.51kg/d) increasing significantly, and yields of fat-corrected milk, energy-corrected milk, and fat tending to increase during this period for cows that had been fed BMRCS. The increased intakes during the last 2wk of the prepartum period in the BMRCS treatment were likely because of a reduction in fill, whereas the increased intakes in the postpartum period in cows fed the BMRCS were either because of the higher intakes during the prepartum period or because of a reduction in fill limitations in the postpartum period. The carryover response in wk 4 to 15 may have resulted from cows that received BMRCS during the transition period being in a more positive nutrient balance than cows fed CCS. The results of this study indicate the importance that digestible NDF can have in transition diets and the long-term production responses that can occur when intake is increased in the transition period.

Hot topic: Apparent total-tract nutrient digestibilities measured commercially using 120-hour in vitro indigestible neutral detergent fiber as a marker are related to commercial dairy cattle performance

Measuring individual feed nutrient concentration is common practice for field dairy nutritionists. However, accurately measuring nutrient digestibility and using digestion values in total digestible nutrients models is more challenging. Our objective was to determine if in vivo apparent total-tract nutrient digestibility measured with a practical approach was related to commercial milk production parameters. Total mixed ration and fecal samples were collected from high-producing cows in pens on 39 commercial dairies and analyzed at a commercial feed and forage testing laboratory for nutrient concentration and 120-h indigestible NDF (iNDF) content using the Combs-Goeser in vitro digestion technique. The 120-h iNDF was used as an internal marker to calculate in vivo apparent nutrient digestibilities. Two samples were taken from each dairy and were separated in time by at least 3wk. Samples were targeted to be taken within 7d of Dairy Herd Improvement (DHI) herd testing. Approved DHI testers measured individual cow milk weights as well as fat and protein concentrations. Individual cow records were averaged by pen corresponding to the total mixed ration and fecal samples. Formulated diet and dry matter intake (DMI) records for each respective pen were also collected. Mixed model regression analysis with dairy specified as a random effect was used to relate explanatory variables (diet nutrient concentrations, formulated DMI, in vivo apparent nutrient digestibilities, and fecal nutrient concentrations) to milk production measures. Dry matter intake, organic matter (OM) digestibility, fecal crude protein (CP) concentration, and fecal ether extract concentration were related to milk, energy-corrected milk, and fat yields. Milk protein concentration was related to CP digestibility, and milk protein yield was related to DMI, OM digestibility, CP digestibility, and ether extract digestibility. Although many studies have related DMI and OM digestibility to milk production under controlled experimental settings, very few have related practical in vivo measures to milk production. By documenting the practical OM digestibility relationship with milk production, nutritionists and scientists may have confidence in this approach for measuring diet performance and collecting nutritional data for commercial dairies.

Efeito de diferentes níveis de concentrado no período pré e pós-parto sobre a produção de leite e escore corporal de vacas leiteiras

This experiment was carried out with the objective of evaluating the effects of different levels of concentrate supplement in the pre and post-parturition periods on milk production and body score of dairy cow. 54 cows in a completely randomized design, distributed in 3 x 2 factorial arrangement, with 3 treatments, 2 periods and 9 repetitions for treatment, were used. The treatments with different levels of concentrate supplement (in dry basis) in the pre-parturition periods (PRE), were: PRE1 = 0% of the body weight (BW); PRE2 = 0.5% of the BW; PRE3 = 1.0% of the BW; and in the post-parturition (POS), were: POS1 = 1kg for each 2.5 kg of produced milk; POS2 = 1kg for each 2.0kg of produced milk and POS3 = 1kg for each 1.5kg of produced milk, above 6 kg of milk a day. The milk weight and body condition scores were evaluated every seven days. There was not significant difference among the treatments of PRE period for milk production, however, it was verified that the increase in the PRE supplementation, improved the average body condition of animals in post parturition period. In the treatments of POS period, there was positive and increasing effect with the increasing supplementation level, on milk production and medium body score of the animals. Improvement was not observed in the milk production with the increase of supplement in the PRE period, but in the POS period there was higher milk production with the increase supplement. There were not correlation among pre-parturition treatments and milk production, but there was correlation of these with body score to the parturition (r=0.66). There was correlation of supplement levels in the post parturition with medium body score (0.36) and with milk production (0.32). It can be concluded that the increasing supplement level in the pre-parturition period improves the body score but not the milk production of the animals. The increase of supplement in the post parturition period gets better so much the body score as the milk production.

Short communication: Projecting milk yield using best prediction and the MilkBot lactation model

The accuracy and precision of 3 lactation models was estimated by summarizing means and variability in projection error for next-test milk and actual 305-d milk yield (M305) for 50-d intervals in a large Dairy Herd Improvement Association data set. Lactations were grouped by breed (Holstein, Jersey, and crossbred) and parity (first vs. later). A smaller, single-herd data set with both Dairy Herd Improvement Association data and daily milk weights was used to compare M305 calculated from test-day data with M305 computed by summing daily milk weights. The lactation models tested were best prediction (BP), the nonlinear MilkBot (MB) model, and a null model (NM) based on a stepwise function. The accuracy of the models was ranked (best to worst) MB, BP, and NM for later-parity cows and MB, NM, and BP for first-parity cows, with MB achieving accuracy in projecting daily milk of 0.5kg or better in most groups. The models generally showed better accuracy after 50d in milk. Best prediction and NM had low accuracy for crossbred cows and first-parity Holstein and Jersey cows. The MB model appears to be more precise than BP, and NM had low precision, especially for M305. Regression of model-generated M305 on summed M305 showed BP and MB to be equally efficient in ranking lactations, but MB was better at quantifying differences.

Effect of Thermal Stress on Reproductive Performance Parameters of Sows with Defined Genotype at the RYR1 locus

Effect of Thermal Stress on Reproductive Performance Parameters of Sows with Defined Genotype at the RYR1 locusThe objective of the present research was to determine the influence of ambient air temperature in the farrowing section of a pig facility on chemical composition, colostrum and milk somatic cell counts (SCC), and rearing efficiency of piglets from Polish Landrace (PL) sows with identified genotype at the RYR1 locus. Subjects were 60 PL sows in the second and third reproductive cycle. Polymorphism at the RYR1 locus was analysed using the PCR-RFLP method. The proportion of RYR1 C/C and RYR1 C/T genotypes in each group was 1:1. Three groups of experimental temperatures were established: I - 22°C, II - 25°C, III - 28°C. The present study demonstrated that sows kept in periodic high ambient temperature (25°C, 28°C) showed a relatively long period of farrowing, more aggressive behaviour and overlying. Variability was also found between the groups with respect to litter size and litter weight, chemical composition and SCC of colostrum and milk. The results indicate that elevated ambient temperature during the perinatal period may adversely affect the utility value of sows.

On-farm estimation of energy balance in dairy cows using only frequent body weight measurements and body condition score

Precise energy balance estimates for individual cows are of great importance to monitor health, reproduction, and feed management. Energy balance is usually calculated as energy input minus output (EBinout), requiring measurements of feed intake and energy output sources (milk, maintenance, activity, growth, and pregnancy). Except for milk yield, direct measurements of the other sources are difficult to obtain in practice, and estimates contain considerable error sources, limiting on-farm use. Alternatively, energy balance can be estimated from body reserve changes (EBbody) using body weight (BW) and body condition score (BCS). Automated weighing systems exist and new technology performing semi-automated body condition scoring has emerged, so frequent automated BW and BCS measurements are feasible. We present a method to derive individual EBbody estimates from frequently measured BW and BCS and evaluate the performance of the estimated EBbody against the traditional EBinout method. From 76 Danish Holstein and Jersey cows, parity 1 or 2+, on a glycerol-rich or a whole grain-rich total mixed ration, BW was measured automatically at each milking. The BW was corrected for the weight of milk produced and for gutfill. Changes in BW and BCS were used to calculate changes in body protein, body lipid, and EBbody during the first 150d in milk. The EBbody was compared with the traditional EBinout by isolating the term within EBinout associated with most uncertainty; that is, feed energy content (FEC); FEC=(EBbody+EMilk+EMaintenance+Eactivity)/dry matter intake, where the energy requirements are for milk produced (EMilk), maintenance (EMaintenance), and activity (EActivity). Estimated FEC agreed well with FEC values derived from tables (the mean estimate was 0.21MJ of effective energy/kg of dry matter or 2.2% higher than the mean table value). Further, the FEC profile did not suggest systematic bias in EBbody with stage of lactation. The EBbody estimated from daily BW, adjusted for milk and meal-related gutfill and combined with frequent BCS, can provide a successful tool. This offers a pragmatic solution to on-farm calculation of energy balance with the perspective of improved precision under commercial conditions.

Analysis of some of the epidemiological risk factors affecting the prevalence of tuberculosis in buffalo at seven livestock farms in Punjab Pakistan

Background: Bovine tuberculosis is a disease of zoonotic importance. It is disease of high priority all over the world and needs to be investigated in each country. Objective: This study was conducted to find out the prevalence of tuberculosis in buffaloes and associated risk factors. Methods: The study was carried out at seven livestock experimental stations in Punjab, Pakistan. Buffaloes were studied by comparative cervical intradermal tuberculin test. Result: The results of the study revealed an overall tuberculosis prevalence of 11.3% with 86% of farms having tuberculin positive animals. The frequency analysis revealed significant difference between different groups for age, calving, lactation length, average daily milk and live weight of the buffaloes. Data analysis by T-test also revealed significant difference between means for age, live weight, calving, lactation length and average daily milk between tuberculin positive and negative buffaloes. Bivariate and multivariate logistic analysis revealed significant association of age, live weight, calving, average daily milk and lactation length. Multivariate logistic regression analysis including all the variables in the model revealed significant association of tuberculosis with age, live weight, total milk produced, presence of cattle at the farm, lactation length, and total other animals at the farm. Conclusion: The prevalence of tuberculosis in buffaloes increases with the increase in age, calving, live weight, milk production and presence of cattle at the farm, while the prevalence decreases with the increase in lactation length. Keywords: Buffaloes, Pakistan, prevalence, tuberculin test, tuberculosis

A field trial on the effect of propylene glycol on milk yield and resolution of ketosis in fresh cows diagnosed with subclinical ketosis

The purpose of this study was to determine the effect of oral propylene glycol (PG) administration on ketosis resolution and milk yield in cows diagnosed with subclinical ketosis (SCK). Cows from 4 freestall dairy herds (2 in New York and 2 in Wisconsin) were each tested 6 times for SCK from 3 to 16 d in milk on Mondays, Wednesdays, and Fridays. Subclinical ketosis was defined as a β-hydroxybutyrate (BHBA) concentration of 1.2 to 2.9mM/L, and clinical ketosis was defined as ≥3.0mM/L. Cows with SCK were randomized to the treatment group (oral PG) or control group (no PG); treatment cows were drenched with 300mL of PG once daily from the day they tested 1.2 to 2.9mM/L until the day they tested <1.2mM/L. Outcomes evaluated for all farms included time from SCK until BHBA test <1.2mM/L or until BHBA test ≥3.0mM/L. Individual milk weights for the first 30 d of lactation were evaluated for the 3 farms monitoring daily milk. Semiparametric proportional hazards models were used to evaluate time to event outcomes; repeated-measures ANOVA was used to assess milk weights. A total of 741 of 1,717 (43.2%) eligible enrolled cows had at least one BHBA test of 1.2 to 2.9mM/L. Of these, 372 were assigned to the treatment group and 369 to the control group. Based on hazard ratios, PG-treated cows were 1.50 times more likely (95% confidence interval=1.26 to 1.79) to resolve their SCK and 0.54 times less likely (95% confidence interval=0.34 to 0.86) to develop clinical ketosis than control cows. Across the 3 herds measuring individual milk weights, treated cows produced 0.23kg more milk per milking in the first 30 d of lactation than control cows, for a total difference of 0.69kg/cow per day. After identification of a treatment by herd interaction, stratification by herd showed that treated cows produced more milk per milking on farm A (0.44kg) and farm B (0.53kg) in the first 30 d of lactation than control cows, for a total difference of 1.34 and 1.59kg/d, respectively; milk production did not differ (0.02kg per milking) between the 2 groups on farm D. These results show the positive effects of oral PG administration in fresh cows with SCK by helping to resolve SCK and preventing clinical ketosis. In addition, oral PG improves milk yield during early lactation in cows diagnosed with SCK.

Hay intake improves performance and rumen development of calves fed higher quantities of milk

Research to date has suggested that access to forage before weaning can limit rumen development in calves, but no research has yet addressed the role of forage for calves fed higher quantities of milk. This study compared performance and rumen development of calves provided high volumes (equivalent to approximately 20% of calf birth weight) of milk with and without access to hay. At d 3 of age, individually housed calves were randomly assigned to treatment (either ad libitum access to chopped grass hay or no forage; n=15 calves per treatment, 10 heifers, and 5 bulls). All calves were provided ad libitum access to water and starter throughout the study. All calves were offered 8L of milk/d from a nipple bottle from d 3 to 35, 4L/d from d 36 to 53, and 2L/d until weaning at d 56. Solid feed intake and growth parameters were monitored from d 3 to 70. At d 70, males from both treatments were slaughtered to measure rumen development parameters. Overall dry matter (DM) intake from solid feed did not differ between treatments before wk 5. However, during wk 6 to 10, calves fed forage consumed more total DM (starter plus hay) than did calves fed no forage. Hip and wither height, heart girth, and body barrel at d 3, 56, and 70 did not differ between treatments. Reticulorumen weight was heavier in calves fed hay versus those fed only starter (12.77±1.29 vs. 7.99±0.69kg with digesta; 1.89±0.05 vs.1.60±0.09kg without digesta). Body weight without digesta was similar in calves fed forage or no forage. Mean rumen pH was higher in calves fed hay compared with those fed no forage (5.49±0.08 vs. 5.06±0.04). In conclusion, provision of chopped hay to calves fed high volumes of milk can promote solid feed DM intake and rumen development without affecting BW gain.

Quantifying shape of lactation curves, and benchmark curves for common dairy breeds and parities

The MilkBot®(DairySight LLC,Argyle, NY; http://milkbot.com) lactation model provides a means of quantifying both shape and magnitude oflactation curves as a set of parameter values, each of which is associated with a single aspect of lactation curve shape. Lactation data may be fitted to the model to summarize a lactation as a set of parameter values which summarize the lactation as a whole. The scale parameter controls magnitude without changing the shape of the curve, the ramp parameter controls steepness of the post-parturient rise in milk production, the decay parameter controls the rate of late lactation decline, and the offset parameter defines a theoretical offset between the start of milk production and calving. The decay parameter is easily re-expressed mathematically as persistence to quantify the rate of decline in production after peak milk. Time and quantity of peak milk, or production for any day or period in the lactation may be calculated directly from parameter values.&#x0D; Aggregate normal lactation curves for mean and median milk production of Holstein, Jersey, Crossbred, Guernsey, Ayrshire, and Brown Swiss dairy cattle, stratified by parity, are calculated from a DHIA data set collected from 2005 through mid-2008 and covering over six million lactations and 51 million milk weights, mainly from farms in the eastern United States. These constitute benchmark curves that may be used as standards for normal milk production, or to quantify changes in normal productivity over time or with respect to other variables, or in econometric studies.

Effects of differential supplementation of fatty acids during the peripartum and breeding periods of Holstein cows: I. Uterine and metabolic responses, reproduction, and lactation

The objectives were to evaluate the effects of differential timing of supplementation of different Ca salts (CS) of fatty acids (FA) on FA profiles of cotyledonary-caruncular tissues, metabolic status, uterine health, pregnancy, pregnancy losses after 2 artificial inseminations (AI), and milk yield. Holstein cows (n=1,380) were assigned randomly to be fed either CS of palm oil (PO) or safflower oil (SO) from 30 d prepartum until 30 d postpartum (dpp) and further randomized to receive either CS of PO or fish oil (FO) from 30 to 160 dpp. Supplementation of CS of FA was at 1.5% of dietary dry matter. Tissues (n=23) and blood (n=32) were collected from a subsample of cows. Blood was collected daily from parturition to 10 dpp and three times weekly thereafter until 30 dpp for analyses of PGF2α metabolite, nonesterified FA, β-hydroxybutyric acid, blood urea nitrogen, and glucose. Cows were evaluated once between 8 to 10 dpp for cervical discharge type. At 43 dpp, cows received 2 injections of PGF2α 14 d apart, followed 14 d later by injections of GnRH at 7 d before and 56h after an injection of PGF2α with AI at 16h after the second GnRH injection. All cows received intravaginally a controlled internal drug-releasing device, containing 1.38g of progesterone, at 18 d after the first AI followed 7 d later by removal of the device and injection of GnRH. Nonpregnant cows at 32 d after AI were injected with PGF2α, followed 56h later with a GnRH injection and second AI 16h thereafter. Cows diagnosed pregnant after both AI were re-examined at 60 d of pregnancy to determine pregnancy losses. Milk weights were recorded monthly for all cows. Caruncular n-6:n-3 FA ratio was greater in cows fed SO. Plasma concentrations of metabolites and frequency of cervical discharge type did not differ between PO- and SO-fed cows. Plasma PGF2α metabolite was greater in SO-fed cows at 4 and 7 dpp. Pregnancy per AI at 32 and 60 d post first AI was not affected by diets, but pregnancy loss was less in FO-fed cows. At second AI, pregnancy was greater in FO-fed cows at 32 d and in SO-FO-fed cows at 60 d post AI. Pregnancy loss after second AI was not affected by diets. Overall pregnancy per AI was greater in cows fed SO followed by FO at 60 d of pregnancy and pregnancy loss was reduced in FO-fed cows. Monthly milk yield was greater (0.7 kg/d) in SO-fed cows. In conclusion, strategic feeding of CS of FA during transition and breeding periods can benefit fertility and milk production of lactating dairy cows.

Energy balance in first-lactation Holstein, Jersey, and reciprocal F1 crossbred cows in a planned crossbreeding experiment

The Virginia Tech crossbreeding project began in the fall of 2002 by mating Holstein (H) and Jersey (J) foundation females to Holstein and Jersey bulls to create HH, HJ, JH, and JJ genetic groups, where the sire breed is listed first followed by dam breed. Collection of individual daily feed intakes began in September 2005 and continued through November 2008, resulting in observations on 43, 34, 41, and 22 HH, HJ, JH, and JJ cows, respectively. Intakes were measured for 2 wk out of every 6-wk period for first-lactation cows less than 310 d in milk. The ration was analyzed for dry matter and nutrient content, which was used to calculate net energy of lactation (NEL, Mcal/kg). Body and milk weights were collected daily with milk components measured monthly. The NEL requirements for maintenance, growth (in the form of retained energy), pregnancy, and production were calculated using National Research Council (2001) equations. Random regression models were used to predict consumed NEL and NEL required for production, maintenance, and body weight at every week in lactation. Energy required for growth was calculated for each cow at each stage of lactation using five 2-mo stages. Energy balance was estimated by subtracting the predicted energy required for production, maintenance, growth, and pregnancy from the predicted NEL consumed. A linear model with fixed effects of genetic group, year-season of calving group, and a linear and quadratic effect of age at calving was used to analyze the energy terms. The HJ and JH groups were not different in any of the analyses for energy terms. The HH cows consumed more energy than did HJ and JJ cows. There were no genetic group differences for total energy for pregnancy. The HH, HJ, and JH groups were not different from each other for energy required for production but required more energy for production than the JJ. The JH allocated a lower percentage of their energy intake to maintenance than the HH (25.7 to 27.4%) and the JJ allocated less energy to growth than the HH and HJ. Genetic group explained significant variation for percentage of energy partitioned to production with the JJ allocating more energy to production than the HH (66.3 vs. 60.9%). Genetic group differences in characterization of energy balance warrant further study.

Effects of Removing Cows from Chronic Oxytocin use During Lactation

The objectives of this study were to investigate the effect of discontinuation of chronic oxytocin supplementation on lactating dairy cows and to determine if there was a difference between methods of discontinuation. The study was conducted on a commercial dairy in central New York milking over 1,200 cows, with more than 80 cows being supplemented with oxytocin prior to the start of the study. Seventy-seven cows receiving supplemental oxytocin were enrolled in the study and randomly assigned to one of four treatment groups: 1) abrupt discontinuation; 2) abrupt discontinuation with a needle stick at the normal time of oxytocin injection; 3) graduated decrease in oxytocin dose; and 4) a control group that was only monitored. Total milk weight, milk in the first two minutes, total milking time, and bimodality of milk flow were measured at every milking for 12 milkings before and after the initiation of the treatment protocol. Non-parametric paired analysis was used within treatment group before and after initiation of treatment, and non-paired analysis was used to analyze differences between treatment groups. Other than the control group, all experimental groups showed a significant decrease in milk production per milking (P&lt;0.005), ranging from 2.8-7.4 lb (1.3-3.4 kg) per milking per cow. None of the cows ceased lactating. There were no significant differences in milk produced in the first two minutes, total milking time, or the number of bimodal milk flows in any of the groups (P&gt;0.09). No significant differences (P&gt;0.11) in the change in milk production per milking or milk produced in the first two minutes were found between the group that underwent graduated discontinuation of oxytocin and the group abruptly removed from oxytocin supplementation without sham injection. These results show that dairy producers can stop supplementing cows with exogenous oxytocin in the parlor by either abrupt discontinuation or a weaning protocol with a loss of milk similar to that gained from oxytocin supplementation, and cows will not cease to lactate.

Effects of sodium sesquicarbonate on dry matter intake and production of milk and milk components by Holstein cows

Forty-six multiparous Holstein cows were used to investigate the effects of sodium sesquicarbonate on dry matter intake, body weight, and production and composition of milk during a 308-d lactation. Diets contained alfalfa silage, corn silage, and concentrate. Composition of diets was changed twice during the 308-d lactation experiment. Diets fed during d 1 to 175 and d 176 to 245 were formulated to contain more rumen-undegradable protein and fat, and less forage than that fed during d 246 to 308. Sodium sesquicarbonate did not affect yields of milk, 4% fat-corrected milk, and components in milk, or percentages of components in milk during the complete 308-d lactation or during d 1 to 175 or d 176 to 245. However, from d 246 to 308, cows fed sodium sesquicarbonate produced more milk, 4% fat-corrected milk, fat, protein, and solids-not-fat than did control cows. Milk composition was not altered. These data suggest that composition of the diet has a significant effect on the response to dietary buffers by lactating dairy cows.

Calcium salts of polyunsaturated fatty acids deliver more essential fatty acids to the lactating dairy cow

Recent research has focused on the importance of supplying essential fatty acids to the lactating dairy cow. The addition of essential fatty acids, specifically linoleic and linolenic acid, to dairy cow diets has been investigated as a method to increase reproductive efficiency. Rumen bacteria, however, biohydrogenate polyunsaturated fatty acids (PUFA) to saturated fatty acids. This is an important issue because it can also lead to milk fat depression when unsaturated fatty acids are fed. The formation of Ca salts has previously been shown to partially protect unsaturated fatty acids from rumen biohydrogenation. The objective of this experiment was to evaluate feed intake, milk production, and milk composition of cows fed Ca salts of palm fatty acids (CS) compared with those fed Ca salts of palm fatty acids with an increased content of PUFA (CS+PUFA). Nineteen lactating Holstein cows were used in a switchback experiment to determine any differences between CS and CS+PUFA on milk production and composition. This experiment consisted of 3 consecutive periods of 14 d. Treatments were formulated to provide 450 g/d (dry matter basis) of the Ca salt supplement and were mixed with the same basal ration. Milk weights and feed intakes were recorded daily for each cow. Milk samples were collected the last 2 d of each period and analyzed for milk composition and fatty acids. Dry matter intake [28.0 vs. 27.0kg/d; standard error of the mean (SEM) = 0.4] and milk production (44.4 vs. 44.0kg/d; SEM = 0.7) were not different between treatments for CS and CS+PUFA, respectively. Milk fat percentage (3.34 vs. 3.22%; SEM = 0.07) and milk protein percentage (2.78 vs. 2.80%; SEM = 0.01) were not different for CS- and CS+PUFA-fed cows. Feeding CS+PUFA reduced the concentration of palmitic acid in milk fat (28.3 vs. 26.8 wt%; SEM = 0.3). Supplementation of CS+PUFA increased the linoleic acid concentration (3.96 vs. 4.61 wt%; SEM = 0.1) of milk fat, indicating that linoleic acid was partially protected from rumen biohydrogenation. Concentrations of conjugated linoleic acid were also increased (0.44 vs. 0.52 wt%; SEM = 0.02) when cows consumed CS+PUFA, indicating that some biohydrogenation did occur. Supplementing CS+PUFA did not alter milk production, milk fat percentage, or dry matter intake when compared with CS. The CS+PUFA supplement supplied more linoleic acid to the small intestine for milk fat synthesis.

Best prediction of yields for long lactations

Lactation records of any reasonable length now can be processed with the selection index method known as best prediction (BP). Previous prediction programs were limited to the 305-d standard used since 1935. Best prediction was implemented in 1998 to calculate lactation records in USDA genetic evaluations, replacing the test interval method used since 1969 to calculate lactation records. Best prediction is more complex but also more accurate, particularly when testing is less frequent. Programs were reorganized to output better graphics, give users simpler access to options, and provide additional output, such as BP of daily yields. Test-day data for 6 breeds were extracted from the national dairy database, and lactation lengths were required to be ≥500 d (Ayrshire, Milking Shorthorn) or ≥800 d (all others). Average yield and SD at any day in milk (DIM) were estimated by fitting 3-parameter Wood's curves (milk, fat, protein) and 4-parameter exponential functions (somatic cell score) to means and SD of 15- (≤300 DIM) and 30-d (>300 DIM) intervals. Correlations among TD yields were estimated using an autoregressive matrix to account for biological changes and an identity matrix to model daily measurement error. Autoregressive parameters (r) were estimated separately for first (r=0.998) and later parities (r=0.995). These r values were slightly larger than previous estimates due to the inclusion of the identity matrix. Correlations between traits were modified so that correlations between somatic cell score and other traits may be nonzero. The new lactation curves and correlation functions were validated by extracting TD data from the national database, estimating 305-d yields using the original and new programs, and correlating those results. Daily BP of yield were validated using daily milk weights from on-farm meters in university research herds. Correlations ranged from 0.900 to 0.988 for 305-d milk yield. High correlations ranged from 0.844 to 0.988 for daily yields, although correlations were as low as 0.015 on d 1 of lactation, which may be due to calving-related disorders that are not accounted for by BP. Correlations between 305-d yield calculated using 50-d intervals from 50 to 250 DIM and 305-yield calculated using all TD to 500 DIM increased as TD data accumulated. Many cows can profitably produce for >305 DIM, and the revised program provides a flexible tool to model these records.

Weight distribution and gait in dairy cattle are affected by milking and late pregnancy

There is increased interest in automated methods for lameness detection, such as measures of weight distribution. Still, practical use of such methods depends on knowing the conditions that affect how cows distribute their weight. In 3 experiments, 10, 18, and 12 Holstein cows were trained to stand on a platform that measured the weight placed on each of their legs. The objectives were to evaluate how cows change their weight distribution after milking, after calving, and when standing with the front legs elevated and to evaluate the effect of the udder fill and fetus weight on the gait score. Comparisons before and after milking and before and after calving showed that the weight of milk was carried mainly on the back legs, whereas the weight of the fetus was distributed between front (52%) and back legs (48%). The percentage of weight distributed between front and back legs was not affected by elevation of the front legs. Weight shifting between contralateral legs was greater before calving than after; the weight variability over time decreased by 30% after calving. A full udder increased gait score by 0.3±0.1 and particularly abduction/adduction of the back legs (increased by 83%). Gait score did not change after calving, although the back arch increased by 25%. Therefore, time since milking and state of late pregnancy need consideration when using gait score and measures of weight distribution to detect lameness.