Angelika Haeussermann

Invited review: Technical solutions for analysis of milk constituents and abnormal milk

Information about constituents of milk and visual alterations can be used for management support in improving mastitis detection, monitoring fertility and reproduction, and adapting individual diets. Numerous sensors that gather this information are either currently available or in development. Nevertheless, there is still a need to adapt these sensors to special requirements of on-farm utilization such as robustness, calibration and maintenance, costs, operating cycle duration, and high sensitivity and specificity. This paper provides an overview of available sensors, ongoing research, and areas of application for analysis of milk constituents. Currently, the recognition of abnormal milk and the control of udder health is achieved mainly by recording electrical conductivity and changes in milk color. Further indicators of inflammation were recently investigated either to satisfy the high specificity necessary for automatic separation of milk or to create reliable alarm lists. Likewise, milk composition, especially fat:protein ratio, milk urea nitrogen content, and concentration of ketone bodies, provides suitable information about energy and protein supply, roughage fraction in the diet, and metabolic imbalances in dairy cows. In this regard, future prospects are to use frequent on-farm measurements of milk constituents for short-term automatic nutritional management. Finally, measuring progesterone concentration in milk helps farmers detect ovulation, pregnancy, and infertility. Monitoring systems for on-farm or on-line analysis of milk composition are mostly based on infrared spectroscopy, optical methods, biosensors, or sensor arrays. Their calibration and maintenance requirements have to be checked thoroughly before they can be regularly implemented on dairy farms.

Accuracy of in-line milk composition analysis with diffuse reflectance near-infrared spectroscopy

Knowledge of daily milk composition changes can assist in monitoring dairy cow health and can help to detect nutritional imbalances. An analytical tool offering the possibility of analyzing milk during the daily milking routine would provide such information. Near-infrared (NIR) spectroscopy can analyze multiple constituents in a given substrate at the same time. In this study, a special NIR in-line milk-analyzing device was designed, and its ability to predict the contents of fat, protein, lactose, and urea and the somatic cell count in milk during the milking process was evaluated. The NIR spectra were acquired with a diode array spectrometer in diffuse reflection in the wavelength range 851 to 1649 nm. The spectra originated from a total of 785 partial milkings out of 84 composite milkings. Corresponding subsamples of the composite milkings were used for reference analysis (n=785). Excellent validation results were obtained with regard to the coefficients of determination (R(2)=0.99, 0.98, and 0.92), and standard errors of prediction (0.09, 0.05, and 0.06) for fat (%), protein (%), and lactose (%), respectively. Satisfying results were achieved for urea content (mg/L) and logarithmically transformed SCC in milk, with R(2) of 0.82 and 0.85 and standard errors of prediction of 19.3 and 0.18, respectively. The accuracy of predicting protein, lactose, and urea contents was in accordance with international recommendations for reproducibility specified for in-line analytical devices.

Rumination activity of dairy cows in the 24 hours before and after calving

Monitoring rumination behavior serves multiple purposes in feeding and herd management of dairy cows. The process of calving is a major event for cows, and a detailed understanding of alterations in behavioral patterns of animals in the time around calving is important in calving detection. The objective of this study was to describe the short-term changes in rumination patterns in dairy cows immediately before and after parturition. In total, 17 cows were fitted with rumination sensors that were able to monitor rumination time, number of rumination boli, and number of rumination jaw movements. Rumination time was decreased in the last 4h antepartum and in the first 8h postpartum. Cows stopped ruminating 123 ± 58 min (mean ± standard deviation) before calving and resumed ruminating 355 ± 194 min after calving. The number of rumination jaw movements and boli per day were decreased in the 24-h period postpartum. Rumination rate, the number of rumination jaw movements per rumination minute, and the number of boli per rumination minute changed little around calving. The calving event primarily influenced the duration and frequency of various rumination characteristics but not rumination intensity. Among detected characteristics, rumination time showed the greatest potential for monitoring of calving events.

Evaluation of Control Strategies for Fogging Systems in Pig Facilities

During hot periods, heat loss from non-sweating animals can be improved by fogging water, in order to cool the ambient air and enhance sensible heat dissipation. A dynamic simulation model was used to test control settings for fogging (turning on the system at 1.5°C and 3°C above setpoint temperature, fogging system duty cycle 30 s and continuous) and ventilation (control range 3°C and 6°C, maximum available ventilation rate 32 and 43 air volume changes per hour). The control settings were evaluated by the number of simulated hours in specific temperature-humidity categories, by maximum temperature-humidity index (THI), as well as by the simulated energy use and water consumption of the control strategies. The validation during four growing-finishing periods resulted in an agreement within the accuracy of the temperature and humidity measurements: the difference between simulated and measured values averaged 0.2°C and 3% RH and 0.6°C and 3% RH with and without evaporative cooling, respectively. The efficacy of the fogging system, as measured by reductions in THI, predicted that alert situations were reduced from 13% to 1%, and all dangerous or emergency situations were eliminated. A year-round simulation resulted in water consumption of 2.5 L pig-1 day-1 if fogging was used on maximum settings and was lowered by about 25% for an optimized ventilation setting, namely a reduced maximum ventilation rate combined with shifting the temperature at which fogging was turned on. The results demonstrate that water and energy consumption can be reduced clearly without considerable negative effects on THI and indoor air climate.

Robustness of near-infrared calibration models for the prediction of milk constituents during the milking process.

The robustness of in-line raw milk analysis with near-infrared spectroscopy (NIRS) was tested with respect to the prediction of the raw milk contents fat, protein and lactose. Near-infrared (NIR) spectra of raw milk (n = 3119) were acquired on three different farms during the milking process of 354 milkings over a period of six months. Calibration models were calculated for: a random data set of each farm (fully random internal calibration); first two thirds of the visits per farm (internal calibration); whole datasets of two of the three farms (external calibration), and combinations of external and internal datasets. Validation was done either on the remaining data set per farm (internal validation) or on data of the remaining farms (external validation). Excellent calibration results were obtained when fully randomised internal calibration sets were used for milk analysis. In this case, RPD values of around ten, five and three for the prediction of fat, protein and lactose content, respectively, were achieved. Farm internal calibrations achieved much poorer prediction results especially for the prediction of protein and lactose with RPD values of around two and one respectively. The prediction accuracy improved when validation was done on spectra of an external farm, mainly due to the higher sample variation in external calibration sets in terms of feeding diets and individual cow effects. The results showed that further improvements were achieved when additional farm information was added to the calibration set. One of the main requirements towards a robust calibration model is the ability to predict milk constituents in unknown future milk samples. The robustness and quality of prediction increases with increasing variation of, e.g., feeding and cow individual milk composition in the calibration model.

Feeding characteristics and rumination time of dairy cows around estrus

Against the background of decreasing reproduction efficiency, estrus detection is gaining increased importance. The objective of this study was to evaluate changes of feeding characteristics and rumination time in dairy cows in the days around estrus. Feeding characteristics were recorded by weighing troughs, and rumination time by acoustic sensors. Analysis included data from 25 primiparous and 37 multiparous cows, which were successfully inseminated (day of insemination=d 0). Feeding time and rumination time were decreased on d -1 and 0, feed intake, and feeding rate on d 0. Primiparous and multiparous cows differed in their reference values, but their feeding and rumination times on the day of insemination were reduced to similar extents. Rumination time was reduced in a time frame of 30 h around estrus whereby the main drop was found during the time period between 0600 h on d -1 and 1200 h on d 0. The change of almost all evaluated feeding characteristics and rumination time around estrus indicated their potential for useful addition in early detection of estrus.

Suitability of feeding and chewing time for estimation of feed intake in dairy cows

Monitoring of feeding and rumination behaviour can provide useful information for dairy herd management. The feeding behaviour of dairy cows can be recorded by different techniques, such as video cameras, weighing troughs or chewing sensors. Among feeding characteristics, individual feed intake of cows is of utmost interest, but as weighing troughs have high space and cost requirements they are used primarily in research studies. The objective of the present study was to evaluate whether records on feeding time or chewing activity or a combination of both contain enough information to estimate feed intake with sufficient accuracy. Feed intake and feeding time per cow were recorded by means of weighing troughs. Concurrently, chewing activity of seven cows was recorded by MSR-ART pressure sensors during five to eight measuring days per cow. Feeding and chewing behaviour were evaluated in time slots (1 min) and additionally assigned to feeding bouts for further analysis. The 1 min time slots were classified into feeding/no feeding or chewing/no chewing by the two systems, and agreement was found in 92.2% of the records. On average, cows spent 270±39 min/day at the feeding troughs and chewed 262±48 min/day. The average fresh matter intake (FMI) was 49.6±5.1 kg/day. Feed intake was divided into 9.7 bouts/day during which cows fed in average 27.8±21.7 min/bout and chewed 27.0±23.1 min/bout. The correlation between FMI and feeding time was r=0.891 and between FMI and chewing time r=0.780 overall cows. Hence, both systems delivered suitable information for estimating feed intake.

Potential of individual cow scatter correction for an improved accuracy of near infrared milk composition analysis

Near infrared (NIR) spectroscopy has the potential to quickly analyse raw milk composition on the farm. The accurate determination of individual cows milk composition changes can indicate health imbalances and, hence, support herd management. The accuracy of NIR calibration models are highly influenced by individual cow scatter effects in the NIR spectra based, to a large extent, on individual scattering effects of milk fat globules (MFG). In this study the potential of an individual cow scatter correction was investigated. A total of 1151 milk samples were taken from 12 Holstein cows and used for spectra acquired in the 851–1649 nm wavelength range with a diode array spectrometer. Corresponding milk samples from the composite milkings were used for reference analysis. Individual cow scatter correction factors were developed from raw milk samples and homogenised milk samples. Calibration models based on the partial least squares (PLS)-regression method from corrected and uncorrected spectra were compared with regard to their prediction accuracy of fat (%), protein (%), lactose (%) and urea content (mgL−1) as well as logarithmised somatic cell count (log SCC) in milk. Prediction of fat content in raw milk was excellent both with and without scatter correction. Improved calibration results were obtained particularly for predicting the content of protein, lactose, urea and log SCC in raw milk when calibration models were based on the corrected spectra. Compared to prediction results of the uncorrected dataset, root mean square error was reduced by up to 25%.

Effect of a multi-sided concave liner barrel design on thickness and roughness of teat-end hyperkeratosis

In a round liner barrel, the force of the closing liner is transferred by the two opposite sides of the liner wall to the teat apex. Liners with a multi-sided barrel shape close at three or more planes and distribute their force to a larger area of the teat apex. The objective of the study was to investigate effects of a liner with a multi-sided concave barrel design on the degree of teat-end hyperkeratosis, thickness and roughness, and on the time delay until thickness or roughness of teat-end hyperkeratosis responded to the experimental liner. The investigations were done on two dairy farms, one in USA and one in Germany. A split-udder arrangement of liners was used, and control treatment was a liner with round barrel shape. The test period comprised 14 weeks in the first study and 16 weeks in the second study. Thickness of teat-end hyperkeratosis was influenced by farm and test week. Roughness was influenced by farm, test week and treatment. In the first study, the incidence of rough teat-end hyperkeratosis was about 28 and 42% lower in teats milked with the experimental liner than in teats milked with the control liner by test weeks 11 and 14, respectively. In the second study, incidence of rough teat-end hyperkeratosis was rare in general, and in addition hardly occurred in teats milked with the experimental liner. The results indicate that the barrel design of the experimental liner causes similar effects on different farms but magnitude of the effect depends on initial incidence of teat end hyperkeratosis in the herd.

Evaluation Method for Improved Control of Adiabatic Air Cooling in Pig Facilities

Especially in hot climate, heat stress decreases feed intake and performance of animals and leads to an increased mortality. Evaporation of water to the ambient air is generally a cost effective solution to alleviate heat stress, but is also critically discussed due to its effect on indoor humidity. The impact of a high pressure fogging system on ventilation, temperature reduction, indoor humidity, water consumption, and evaporation efficiency was investigated in a research facility for fattening pigs during a total of four fattening periods. Measured reductions of the indoor temperature ranged up to 7°C, ventilation rate was reduced by about 22 %, and water consumption averaged on 4 to 5 liters per pig per day at mean daily outside temperatures above 14°C. Performance of the animals was reduced during hot periods when no cooling was used, but were in general compensated afterwards. Evaporation efficiency for a fixed pressure (7 MPa) did depend mainly on temperature and saturation deficit and was 67 % for cold and wet indoor conditions (13°C; 83 % r. h.) and up to 100 % for indoor temperatures around 28°C. To simulate the effect of the cooling system at different outside conditions, a data-based model was created and used as sub-model part in an established dynamic simulation model. The comparison of indoor temperature-humidity profiles, as well as the consideration of water and energy consumption enabled general recommendations for the settings of ventilation and fogging control, like a reduced maximum ventilation rate combined with shifting the fogging start. Pulse cycles instead of continuously fogging featured minor advantages compared to other changes of settings. An adequate control of a fogging system is generally recommended but depends on the specific outside and facility characteristics.