Response of ewes to machine milking: evaluation of the milk flow curves

Abstract

Bimodality is one of the most important indicators of milk ejection reflex during milking without the udder stimulation. The milk ejection reflex is an essential component for complete milk removal during milking. The objective of this study was to evaluate the reaction of dairy sheep, which are bred in Slovakia, on machine milking. The trial was performed with 80 ewes of three breeds and their crosses: Tsigai (TS -17 purebred pieces, TSxLC -13 pieces Tsigai crosses with 50% of Lacaune), Improved Valachian (IV - 22 pieces purebred, IVxLC - 9 pieces Improved Valachian with 50-75% of Lacaune) and Lacaune (LC - 19 pieces). Ewes were milked twice daily during three consecutive days in May. The equipment for graduated electronic milk recording in jar was used and the computer was recording the level of milk in jar in the second intervals. We measured in total 183 milk flow curves. These curves were classified into four groups: 1 peak (1P), 2 peaks (2P, bimodal curves), plateau I (PI, peak flow over 0.4 l/min), and plateau II (PII, peak flow less than 0.4 l/min). The last two types refer to ewes with milk flow having steady state phase longer than 20 s). The frequency of different curve types (1P:2P:PI:PII) was 37:61:2:0 for TS, 21:57:22:0 for TSxLC, 36:47:8:9 for IV, 14:48:29:9 for IVxLC, 17:37:30:15 for LC, respectively. The highest milk production was found in ewes with PI (0.504±0.027 l) as compared with 2P (0.416 ± 0.019 l), 1P (0.321 ± 0.025 l) and PII (0.351 ± 0.049 l P < 0.004) type of curves (Table 2). Total milk yield differed among breeds (TS, IV, LC) and their crosses (TSxLC, IVxLC) (0.358 ± 0.026 l, 0.331 ± 0.022 l 0.433 ± 0.021 l, 0.429 ± 0.030 l, 0.445 ± 0.033 l, P < 0.003 l, respectively) (Table 3). However, no effect of breeds and their crosses was found on machine yield – yield without stripping (0.283 ± 0.024 l, 0.269 ± 0.022 l, 0.319 ± 0.020 l, 0.341 ± 0.028 l, 0.348 ± 0.031 l, P < 0.08). Amount of milk obtained during first emission of 2P was 66,84 ± 1,72 % from machine milk yield and did not differ among breeds and their crosses (64 ± 5 %, 60 ± 5 %, 72 ± 5 %, 71 ± 5 %, 72 ± 6 %, resp., P < 0.4). In conclusion, this is the first study dealing with the evaluation of milkability of TS and IV and their response to machine milking. However, further measurements are needed to obtain more generalised information concerning ability of main Slovakian breeds of sheep for machine milking and their use in milking parlour.