Effects of short and long milking intervals on milking characteristics and changes of milk constituents during the course of milking in crossbred Istrian × Awassi × East-Friesian ewes.

The main objective of this experiment was to evaluate the effects of two milking intervals (8 and 16 h) on milk constituents (fat, protein, lactose, dry matter, and log10 SCC) of nineteen Istrian × Awassi × East-Friesian crossbred ewes in different milk fractions (0-25, 25-50, 50-75 and 75-100%) during the course of milking and in machine stripping (MS) milk. Furthermore, we sought to determine the effect of the two milking intervals on milking characteristics (average milk flow rate, peak milk flow rate, machine-on time, total milk yield, and milk production rate) and whether each milk constituent within each milking interval is best described by a linear, quadratic, or cubic function. Average milk flow rate and milk yield per milking decreased in the 8 h milking interval compared to the 16 h milking interval (P < 0.05). Peak milk flow rate, machine-on time, and milk production rate were not different between the two milking intervals. Overall, milk fat content, dry matter content, and log10 SCC increased in the 8 h milking interval compared to the 16 h milking interval (P < 0.05). Milk protein content did not change through the main milk fractions at either milking interval. Milk lactose content did not change through the milk fractions at the 8 h milking interval, whereas it decreased in the 75-100% and stripping milk fractions at the 16 h milking interval (P < 0.05). The 0-25% and stripping milk fractions contained the highest log10 SCC compared to all other milk fractions (P < 0.05). Changes of milk fat and dry matter content throughout milking were best described by quadratic functions, whereas milk protein content, milk lactose content, and log10 SCC were best described by different functions depending on the milking interval. These results demonstrate that milking interval influenced all milk constituents in various milk fractions during the course of ewe milking. Moreover, milking characteristics such as average milk flow and total milk yield, and the appropriate mathematical function to characterize milk constituents throughout a milking, were affected by milking interval.

Cyclic pressure applied to cows' teats by teatcup liners can be determined simply and noninvasively.

Liner overpressure is a quantitative variable indicating the extent to which the vacuum difference across the liner during phase d (the liner compression phase) of milking machine pulsation exceeds the vacuum difference that would be just sufficient to stop milk flow from the teat. Previously defined methods of determining liner overpressure have required modifications to the milking machine, complex instrumentation, or both. Our method of measuring derived overpressure (OP) offers relatively simple instrumentation and realistic milking machine characteristics. We determined derived OP by measuring the duration of milk flow within a pulsation cycle, and then comparing that duration with the shape of the pulsation curve to deduce the pulsation chamber vacuum level corresponding to that duration. Derived OP by our method yielded measurements of OP that differed by less than 2.0 kPa from those determined by the most practical previous method, for 2 trial liners. Derived OP can serve as a method for comparing and evaluating liners, and the method we developed may also be applied to automatic control of the milking process.

Infrared Thermography of Teat in French Dairy Alpine Goats: A Promising Tool to Study Animal-Machine Interaction during Milking but Not to Detect Mastitis.

There is a need to develop tools for mastitis management in goats and to measure the effects of milking machines on teats. Infrared thermography (IRT), as shown in cows, was a good candidate for early mastitis detection and focusing on milking equipment and settings implicated in potential problems. The aim of this study was to test IRT to detect udder inflammation and the effects of mechanical milking on teats in relation to inflammation status, udder balance, and teat shape in Alpine goats. IRT spectra were compared before and after milking in 551 goats from three commercial herds compared to their individual SCC (somatic cell count). We found no regression or trend between logSCC and IRT measurement or response to milking, even in highly inflamed goat udders. The effect of milking was significant (p < 0.05) with global temperature reduction after milking, but differences were seen between teat parts and unbalanced half udders. The highest reduction in skin temperature was observed at the teat orifice (-1.06 ± 0.05) and the lowest at the teat barrel (-0.37 ± 0.05). The teats with long barrels showed more IRT reactions, which clearly indicates poor adaptation to the liners used. In conclusion, the IRT was not able to detect mastitis, but it is a good tool to diagnose the effects of the milking machine in order to adapt milking equipment and settings to the goats and improve their welfare.

The effects of incomplete milking and increased milking frequency on milk production rate and milk composition1.

Increased milking frequency and incomplete milking have differential effects on milk yield and mammary gland physiology that are important for optimization of milking practices in dairy herds. The objectives of this experiment were to determine the effects of increased milking frequency and incomplete milking on milk production rate (MPR) and milk composition and to determine if milking 3 times daily (3×) could rescue the negative production effects of incomplete milking. Twenty-two multiparous cows were enrolled onto this experiment beginning at 5 days in milk (DIM) and continuing through 47 DIM. A split-plot design was used to randomize the 2 treatments, which were milking frequency and incomplete milking. Eleven cows were randomly assigned to be milked 2 times (2×) daily and 11 cows were randomly assigned to be milked 3×. Within each cow, a contralateral half-udder was randomly assigned to be incompletely milked (30% milk remaining in the gland; IM), and the other half-udder was randomly assigned to be milked completely (CM). Quarter-level milk yields were recorded at each milking session. Milk samples from all quarters were collected twice weekly at the beginning of the morning milking for analysis. Cows milked 2× tended to have reduced MPR compared with 3× milked cows (1.81 ± 0.06 vs. 1.97 ± 0.06 kg milk/h; P = 0.06). Half-udders that were CM and IM produced 1.09 ± 0.03 and 0.80 ± 0.03 kg milk/h, respectively. There was an interaction between incomplete milking treatment and week of lactation (P = 0.04). No interaction was detected between milking frequency and incomplete milking for MPR or milk components. Cows milked 3× had increased milk fat percent (1.93 ± 0.09% vs. 1.65 ± 0.09%, P = 0.047), decreased milk lactose percent (4.80 ± 0.04% vs. 4.93 ± 0.04%, P = 0.04), and exhibited no differences in milk protein percent or milk somatic cell count (SCC) compared with cows milked 2×. Half-udders that were IM had increased milk fat percent (2.15 ± 0.07% vs. 1.43 ± 0.07%, P < 0.0001), decreased lactose percent (4.75 ± 0.03% vs. 4.99 ± 0.03%, P < 0.0001), increased milk log10SCC (4.22 ± 0.05 vs. 4.41 ± 0.05, P = 0.0004), and no differences in milk protein percent compared with CM half-udders. These results indicate that a 3× milking frequency in IM half-udders was not able to improve milk production compared with IM half-udders milked 2×. Our results indicate that 30% milk remaining in the gland had an irreversible impact on milk yield as increased milking frequency was not able to reverse the milk yield lost.