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The effect of exogenous oxytocin on milkability and milk composition in ewes differed in milk flow pattern
Small Ruminant Research 113 (2013) 254–257
Contents lists available at SciVerse ScienceDirect
Small Ruminant Research journal homepage: www.elsevier.com/locate/smallrumres
Short communication
The effect of exogenous oxytocin on milkability and milk composition in ewes differed in milk flow pattern J. Antoniˇc c , V. Tanˇcin a,c,∗ , M. Uhrinˇcat’ a , L. Maˇcuhová a , J. Maˇcuhová b , L. Jackuliaková c a b c
Animal Production Research Centre Nitra, Hlohovecká 2, 951 41 Luˇzianky, Slovak Republic Institute for Agricultural Engineering and Animal Husbandry, Poing, Germany Slovak University of Agricultural in Nitra, Trieda A. Hlinku 2, 949 01 Nitra, Slovak Republic
a r t i c l e
i n f o
Article history: Received 16 January 2013 Received in revised form 12 March 2013 Accepted 14 March 2013 Available online 29 April 2013 Keywords: Milking Ewes Ejection Milkability Oxytocin
a b s t r a c t During milking routine in sheep, the cluster is attached without pre-stimulation and milk ejection occurred (or not) as a consequence of liner movement on teat. The goal was to describe the importance of milk ejection before cluster attachment on milk flow patterns, milk composition and other parameters of milkability of ewes with two different physiological responses to usual milking (ewes with one emission of milk, i.e. expected no milk ejection (1P) and ewes with two emissions of milk i.e. expected milk ejection (2P)). On the base of three pre-experimental consecutive milkings, 22 adult lactating dairy ewes of two breeds Tsigaj (n = 11) and Improved Valachian (n = 11) were selected from the herd of experimental farm of APRC Nitra for this study. The animals were divided into two groups (first group 1P – ewes, and second group 2P – ewes). Ewes were regularly milked two times a day. Milk flow data were recorded during two evening milkings with 48 h in between. During the first measurement the half of the animals in each group was treated by 5 UI i.m. of oxytocin (OT) and the second half by physiological saline (SA) 60 s before the cluster attachment. The application of OT and SA in both groups was changed in cross-over design during the second evening milking. Milk flow kinetics were recorded individually using an electronic jar with 2-wire compact magnetostrictive level. The OT treatment caused shortening of the milking time, increasing of peak milk flow rate and milk yield in thirty seconds in both groups. There were not any changes in milk composition in 2P ewes between SA and OT treatment. In 1P ewes, there was significantly increased total milk yield, machine milk yield, peak flow rate, milk yield in thirty and in 60 s in OT treatment. Moreover, the increased fat yield was recorded in 1P group after OT treatment only. In conclusion, milk ejection occurrence before cluster attachment influences differently the milkability and milk composition in ewes differed in milk flow patterns during usual milking. Thus milk ejection is crucial in our breed for milk yield and composition recording. © 2013 Elsevier B.V. All rights reserved.
1. Introduction There are many farms in Slovakia where ewes are handmilked, though the history of machine milking is dating
∗ Corresponding author. Tel.: +421 903 546 401; fax: +421 376 546 483. E-mail address: [email protected] (V. Tanˇcin). 0921-4488/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.smallrumres.2013.03.011
back to the beginning of 1960s. However, the number of farms with machine milking or interest to milk the sheep with machine is increasing in the last decade. The analysis of milk flow curves are used for monitoring of milk ejection occurrence during machine milking (Labussière, 1988; Bruckmaier et al., 1997; Dˇzidic´ et al., 2004; Maˇcuhová et al., 2008) indicating a positive physiological response of ewes, i.e. OT release, to machine stimuli.
J. Antoniˇc et al. / Small Ruminant Research 113 (2013) 254–257
Few types of milk flow were characterized in ewes. First type (1P, one emission) represents milk flow curves with one peak of milk flow before stripping when no OT release is expected in response to milking. Second type (2P, two emissions) represents milk flow with two clearly separated milk flow peaks when endogenous OT is released. With increasing milk production, the milk ejection can occur before removal of cisternal milk and thus the second peak of milk flow is masked, i.e. plateau milk flow (PL) (Marnet et al., 1998). Also larger volume of cistern and higher production could be a reason of PL due to the limitation of teat canal even if OT is not released during milking. Recently, it was found out that the volume of residual milk of ewes with PL was higher than in 2P, suggesting that not all ewes with PL released OT or milk ejection occurred during milking (Maˇcuhová et al., 2012). In dairy practice, there is not performed any teat stimulation before the cluster is attached to the teat as it is common in dairy cows (Tanˇcin et al., 2007). Thus the parameters of milkability, especially milk flow kinetic, depend on the physiological response of ewes to machine stimulation. There were reductions of 2P milk flow curves occurrence after pre-stimulation (Bruckmaier et al., 1997). Pre-stimulation causing OT release before the cluster is attached to the teat could significantly change the parameters of milkability as it was recently found out with administration of exogenous OT (Antoniˇc et al., 2013). However, we did not test the response of ewes with different milk flow kinetic during usual milking to exogenous OT in that study. Milk distribution in the udder of ewes differs from that of a cow. In ewes, large amount of milk is stored in the cistern that is available for mechanical removal only. However, the amount of milk stored in alveoli is important for milk production and fat yield as well. Normally, machine milking causes an OT release via a neuroendocrine reflex and milk ejection. Moreover, OT release is very important to stimulate milk secretion through alveoli emptying (Zamiri et al., 2001; Silanikove et al., 2010). However, machine milking could sometimes be associated with some kind of stress causing significant reduction of milk yield as a consequence of inhibition of OT release causing 1P flow (Bruckmaier et al., 1997; Negrão and Marnet, 2003) in ewes. The important role affecting OT release is adaptation of different breeds to machine stimulation. Tsigai and Improved Valachian have been shown to have relatively high percentage of 1P and 2P milk flow patterns (Maˇcuhová et al., 2008; Tanˇcin et al., 2011; Kulinová et al., 2012). Therefore, to evaluate the milkability and milk composition of above mentioned breeds during milk recording, the milk flow patterns could be taken into account. The hypothesis was that pre-stimulation (simulated by administration of exogenous OT injection) before cluster attachment will differently influence milkability and milk composition in ewes differed in milk flow pattern (1P versus 2P) during usual milking. The goals of our investigation were to evaluate the importance of milk ejection before cluster attachment on milk flow patterns, milk composition and other parameters of milkability related to physiological response of ewes to usual milking (1P and 2P response).
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2. Materials and methods 2.1. Animals and milking management Twenty-two adult lactating dairy ewes of 2 breeds Tsigai (TS, n = 11) and Improved Valachian (IV, n = 11) with healthy udders (on the base of visual control of mammary gland and sensory evaluation of milk) from the experimental farm of the Animal Production Research Centre in Nitra, Slovakia, were selected from the flock of 400 ewes. Ewes were selected on the basis of milk flow pattern from three consecutive previous milkings before the experiment started. They were on their 3rd–8th lactation and had similar stage of lactation (100 ± 15 days in milking). 11 ewes with 1P type (1P group: 5 TS and 6 IV ewes) and 11 ewes with 2P type (2P group: 6 TS and 5 IV ewes) of milk flow were selected for the experiment. Ewes were milked routinely twice daily at 8:00 and 20:00 h with machine stripping. Machine milking took place in a 1 × 24 low-line sideby-side milking parlour with 12 milking units by one milking technician. The milking machine was set to provide 160 pulsations per minute in a 50:50 ratio with a vacuum level of 39 kPa. During each milking the ewes received 0.1 kg per head concentrate in parlour. 2.2. Experimental procedure Experimental milkings were performed during 2 evening milkings with one evening milking in between without any treatment and milk flow recording to recover the alveolar milk volume in OT treated animals. During the first measurement, half of the animals of each group were i.m. injected with 5 IU of oxytocin (OT treatment) and the second half with physiological saline (SA treatment) 90 s before the cluster attachment. The application of OT and SA in both groups was changed in cross-over design during the second evening milking. 2.3. Samples collection and analysis Milk flow kinetics were recorded individually using an electronic jar that continuously collected the milk during milking. Within the jar there was a 2-wire compact magnetostrictive level transmitter (NIVOTRACK, NIVELCO Ipari Elektronika Rt, Budapest, Hungary) connected to a computer. The milk level in the jar was continuously measured by a transmitter that recorded the signals on a computer once per second. The registered data were processed with Microsoft Excel® . Milk flow curves were evaluated according to Bruckmaier et al. (1997), Rovai et al. (2002) and Maˇcuhová et al. (2008) into 3 types (1peak (1P), 2peaks (2P), plateau (PL)) to select the animals with 1P and 2P milk flow types as well as to record the change in response to OT treatment. The milk flow pattern was calculated using a formula by Maˇcuhová et al. (2007): Milk flow rate (L min
−1
) = (Ln − Ln−4 ) × 15,
L − milk yield in liters,
n − time in s, n > 3 s. From the measured parameters the following data were evaluated: total milk yield (TMY, L), machine milk yield (MMY, L), stripped milk yield (SMY, L), stripped milk yield (SMY, %), milking time (MT, s), peak flow rate (PFR, L min−1 ), time to peak flow rate (TPFR, s), milk yield in 30 s (MY30S, L), milk yield in 60 s (MY60S, L). After each milking, the individual milk samples were collected from the jar for composition analysis. The milk composition was analyzed for percentage of fat, protein, lactose, total solids and solids-not-fat with MilkoScan FT120 (Foss, Hillerød, Denmark). Somatic cells count (SCC) was analyzed with Somacount 150 (Bentley Instruments, Inc., Chaska, Minnesota) analyzer. Fat yield was calculated by using formula: Fat [g] =
TMY [L] × × fat [%] ; 100
= 1038 kg m
−3
2.4. Statistical analysis Totally 42 milk flow curves and 42 milk samples from 21 ewes were evaluated and analyzed by Statistica programme (version 8.0, StatSoft. Inc.). One ewe from OT treatment was removed from statistical evaluation due to no milk flow during milking. T-test of dependent samples was used for comparison of milkability parameters and milk composition between
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J. Antoniˇc et al. / Small Ruminant Research 113 (2013) 254–257
Table 1 Milking characteristics in ewes in one (1P) and two peaks (2P) group of milk flow in response to saline (SA) and oxytocin (OT) treatment (mean ± S.E.M.). Parameter
TMY, L MMY, L SMY, L SMYF, % MT, s PFR, L min−1 TPFR, s MY30S, L MY60S, L
1P group
2P group
S.E.M.
SA treatment
OT treatment
SA treatment
OT treatment
0.19aA 0.08aA 0.11 55.5a 44.3 0.52A 18.6 0.06A 0.07aA
0.24B 0.13B 0.11 45.9 35.5 0.78B 14.7 0.10B 0.12B
0.29b 0.18b 0.11 37.9b 54.6A 0.80A 18.8 0.09A 0.15b
0.28 0.17 0.11 38.4 27.0B 1.12B 14.9 0.14B 0.16
0.01 0.02 0.03 3.01 4.30 0.07 1.64 0.01 0.01
TMY: total milk yield; MMY: machine milk yield; SMY: stripped milk yield; SMYF: stripped milk yield fraction; MT: milking time; PFR: peak flow rate; TPFR: time to peak flow rate; MY30S: milk yield in 30 s; MY60S: milk yield in 60 s. Means in the same line with different letters are different (p ≤ 0.05). a,b Between the groups within treatment. A,B Between treatments within group.
treatments within each group. For comparison of milkability parameters and milk composition between the groups within treatment, the T-test of independent samples was applied.
3. Results After OT treatment, milk flow curves changed: from 11 ewes in 2P group, 8 ewes had 1P and 3 ewes still had 2P; from 11 ewes in 1P group, 9 ewes had 1P, 1 ewe had PL and surprisingly 1 ewe had no milk flow after the OT treatment. The characteristics and milk composition in response to SA and OT treatment in ewes with 1P and 2P type of milk flow are shown in Tables 1 and 2. TMY and MMY did not differ between treatments in 2P group. But in 1P group, TMY and MMY increased after OT treatments. On the other hand OT treatment reduced MT in 2P group. Milk components differed only in total fat yield between treatments or between groups. Fat yield was significantly lower after SA than OT treatment in 1P group and there were no differences between treatments in 2P group. There were not any other significant differences in SCC between treatments within group and between groups within treatments. 4. Discussion OT injection should compensate pre-milking stimulation, which results in the presence of alveolar milk in the cistern, before the cisternal milk is removed as pointed out
Marnet and McKusick (2001). Thus we could demonstrate different changes in milking characteristics in OT treatment milking of ewes depending on the milk flow pattern during SA milking. In both 1P and 2P groups, MT decreased and PFR increased after OT treatment indicating more effective milk removal process. But only in 1P group, milk yield increased after OT treatment, as a consequence of no OT release during SA milking. There was also a reduction of bimodal curves in 2P group after OT treatment. On the other side Bruckmaier et al. (1997) observed that pre-stimulation caused a reduction of 1P curves and an increase 2P curves when blood samples were taken. However, these changes in milk flow were caused by experimental stress during blood sampling causing the delay of oxytocin release. The fat content is higher in alveolar milk than cisternal (McKusick et al., 2002; Castillo et al., 2008; Gómez-Cortés et al., 2011) so it can be expected higher percentage of fat in 2P group than in 1P group during the SA treatment. Opposite results were found out where the numerically higher fat % in 1P versus 2P group could be ascribed to lower milk yield in 1P group because with reduction of milk yield the % of fat is increasing (Ploumi et al., 1998). On the other hand, a significantly higher fat yield in 2P group indicates the removal of alveolar milk. Therefore, due to fat distribution in the udder and the occurrence of milk ejection, there was significant increased fat yield (g) in milk after OT treatment in 1P group only. Ewes of both breeds TS and IV with 1P had significantly higher residual volume of milk than ewes with
Table 2 Milk composition in ewes in one (1P) and two peaks (2P) group of milk flow in response to saline (SA) and oxytocin (OT) treatment (mean ± S.E.M.). Parameter
Fat, % Fat yield, g Protein, % Lactose, % Solids-not-fat, % Total solids, % SCC (lnx )
1P group
2P group
S.E.M.
SA treatment
OT treatment
SA treatment
OT treatment
8.63 17.0aA 5.86 4.66 11.41 19.8 11.64
9.29 22.9B 5.82 4.68 11.39 20.4 11.75
8.31 25.2b 5.48 4.75 11.08 19.2 11.00
8.75 25.2 5.51 4.73 11.1 19.6 11.07
Means in the same line with different letters are different (p ≤ 0.05). a,b Between the groups within treatment. A,B Between treatments within group.
0.13 1.06 0.09 0.03 0.09 0.18 0.06
J. Antoniˇc et al. / Small Ruminant Research 113 (2013) 254–257
2P (Maˇcuhová et al., 2012). These changes in our experimental groups were caused by removing higher amount of residual milk in 1P due to the lacking of endogenous OT effect during SA milking than in 2P group. PFR was significantly influenced by OT treatment in both 1P and 2P groups of ewes. In both groups during OT treatment it could not be observed any PL milk flow. This could be affected by low milk production, because steady state (plateau – PL) milk flow is always seen in higher yielding ewes in our conditions (Tanˇcin et al., 2011) or in other breeds (Rovai et al., 2002). PFR reduced in a course of lactation in older ewes in comparison with primiparous ewes (Casu et al., 2008) expecting larger cistern with lower intrammamary pressure. Probably the effect of OT treatment could not be so effective to increase the PFR in group of ewes with PL flow as with 1P or 2P, but additional study should be done to see the effect of exogenous OT on PFR in ewes with PL milk flow it means under higher milk production. PFR is considered as the most relevant measurement to characterize the ewes’ machine milking speed due to the high repeatability and the favourable correlation with MT (Casu et al., 2008). Thus in our breeds PFR under one or two emissions milk flows is not as exact as in ewes with PL milk flows. Under such low milk yield of our breeds with higher occurrence of 1P milk flow types we probably could not use the PFR as reasonable traits to evaluate milkability during milk recording. Also fat yield in milk from ewes with 1P milk flow does not correspond to the real situation in the udder. 5. Conclusion The milk ejection reflex induced before cluster attachment influenced parameters of milkability and milk composition depending on the physiological response of ewes to usual machine stimulation. Thus influenced parameters of milkability and milk composition could be limited for their importance in milk recording. This study contributes to the knowledge about physiological adaptability and suitability of above mentioned breeds to machine milking. Acknowledgement This study was funded by the Operational Programme for Research and Development project “CEGEZ No. 26220120042” and “MLIEKO No. 26220220098” of the European Regional Development Fund. References Antoniˇc, J., Maˇcuhová, L., Uhrinˇcat’, M., Tanˇcin, V., 2013. The effect milk ejection occurrence before or during machine milking on milkability and milk composition of ewes. Vet. Med. Zoot. 61, 3–7.
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Bruckmaier, R.M., Paul, G., Mayer, H., Schams, D., 1997. Machine milking of Ostfriesian and Lacaune dairy sheep: udder anatomy, milk ejection and milking characteristics. J. Dairy Res. 64, 163–172. Castillo, V., Such, X., Caja, G., Salama, A.A.K., Albanell, E., Casals, R., 2008. Changes in alveolar and cisternal compartments induced by milking interval in the udder of dairy ewes. J. Dairy Sci. 91, 3403–3411. Casu, S., Marie-Etancelin, C., Robert-Grani, C., Barillet, F., Carta, A., 2008. Evolution during the productive life and individual variability of milk emission at machine milking in Sardinian × Lacaune back-cross ewes. Small Rumin. Res. 75, 7–16. ´ A., Kaps, M., Bruckmaier, R.M., 2004. Machine milking of Istrian Dˇzidic, dairy crossbreed ewes: udder morphology and milking characteristics. Small Rumin. Res. 55, 183–189. Gómez-Cortés, P., Mantecón, A.R., Fuente de la, M.A., Manso, T., 2011. Milk composition and fatty acid profile of residual and available milk from ewes fed with diets supplemented with different vegetable oils. Small Rumin. Res. 97, 72–75. Kulinová, K., Maˇcuhová, L., Uhrinˇcat’, M., Tanˇcin, V., 2012. The effect of stressful treatment before and during milking on milkability of dairy ewes. Vet. Med. Zoot. 57, 39–43. Labussière, J., 1988. Review of physiological and anatomical factors influencing the milking ability of ewes and the organization of milking. Livest. Prod. Sci. 18, 253–274. Maˇcuhová, L., Tanˇcin, V., Uhrinˇcat’, M., Maˇcuhová, J., 2012. The level of udder emptying and milk flow stability in Tsigai. Improved Valachian and Lacaune ewes during machine milkings. Czech J. Anim. Sci. 57, 240–247. Maˇcuhová, L., Uhrinˇcat’, M., Maˇcuhová, J., Margetín, M., Tanˇcin, V., 2008. The first observation of milkability of the sheep breeds Tsigai. Improved Valachian and their crosses with Lacaune. Czech J. Anim. Sci. 53, 528–536. ˇ Maˇcuhová, L., Uhrinˇcat’, M., Marnet, P.G., Margetín, M., Mihina, S., Maˇcuhová, J., Tanˇcin, V., 2007. Response of ewes to machine milking: evaluation of milk flow kinetic. Slovak J. Anim. Sci. 40, 89–96 (in Slovak). Marnet, P.G., McKusick, B.C., 2001. Regulation of milk ejection and milkability in small ruminants. Livest. Prod. Sci. 70, 125–133. Marnet, P.G., Negrão, J.A., Labussière, J., 1998. Oxytocin release and milk ejection parameters during milking of dairy ewes in and out natural season of lactation. Small Rumin. Res. 28, 183–191. McKusick, B.C., Thomas, D.L., Berger, J.M., Marnet, P.G., 2002. Effect of milking interval on alveolar versus cisternal milk accumulation and milk production and composition in dairy ewes. J. Dairy Sci. 85, 2197–2206. Negrão, J.A., Marnet, P.G., 2003. Cortisol, adrenalin, noradrenalin and oxytocin release and milk yield during milkings in primiparous ewes. Small Rumin. Res. 47, 69–75. Ploumi, K., Belibasaki, S., Triantaphyllidis, G., 1998. Some factors affecting daily milk yield and composition in a flock of Chios ewes. Small Rumin. Res. 28, 89–92. Rovai, M., Such, X., Caja, G., Piedrafita, J., 2002. Milk emission during machine milking in dairy sheep. J. Anim. Sci. 80 (Suppl. 1), 5. Silanikove, N., Leitner, G., Merin, U., Prosser, C.G., 2010. Recent advances in exploiting goat’s milk: quality, safety and production aspects. Small Rumin. Res. 89, 110–124. Tanˇcin, V., Uhrinˇcat’, M., Maˇcuhová, L., Bruckmaier, R.M., 2007. Effect of pre-stimulation on milk flow pattern and distribution of milk constituents at a quarter level. Czech J. Anim. Sci. 52, 117–121. Tanˇcin, V., Maˇcuhová, L., Oravcová, M., Uhrinˇcat’, M., Kulinová, K., Roychoudhury, Sh., Marnet, P.G., 2011. Milkability assessment of Tsigai, Improved Valachian, Lacaune and F1Crossbred ewes (Tsigai × Lacaune. Improved Valachian × Lacaune) throughout lactation. Small Rumin. Res. 97, 28–34. Zamiri, M.J., Qotbi, A., Izadifard, J., 2001. Effect of daily oxytocin injection on milk yield and lactation length in sheep. Small Rumin. Res. 40, 179–185.
Contents lists available at SciVerse ScienceDirect
Small Ruminant Research journal homepage: www.elsevier.com/locate/smallrumres
Short communication
The effect of exogenous oxytocin on milkability and milk composition in ewes differed in milk flow pattern J. Antoniˇc c , V. Tanˇcin a,c,∗ , M. Uhrinˇcat’ a , L. Maˇcuhová a , J. Maˇcuhová b , L. Jackuliaková c a b c
Animal Production Research Centre Nitra, Hlohovecká 2, 951 41 Luˇzianky, Slovak Republic Institute for Agricultural Engineering and Animal Husbandry, Poing, Germany Slovak University of Agricultural in Nitra, Trieda A. Hlinku 2, 949 01 Nitra, Slovak Republic
a r t i c l e
i n f o
Article history: Received 16 January 2013 Received in revised form 12 March 2013 Accepted 14 March 2013 Available online 29 April 2013 Keywords: Milking Ewes Ejection Milkability Oxytocin
a b s t r a c t During milking routine in sheep, the cluster is attached without pre-stimulation and milk ejection occurred (or not) as a consequence of liner movement on teat. The goal was to describe the importance of milk ejection before cluster attachment on milk flow patterns, milk composition and other parameters of milkability of ewes with two different physiological responses to usual milking (ewes with one emission of milk, i.e. expected no milk ejection (1P) and ewes with two emissions of milk i.e. expected milk ejection (2P)). On the base of three pre-experimental consecutive milkings, 22 adult lactating dairy ewes of two breeds Tsigaj (n = 11) and Improved Valachian (n = 11) were selected from the herd of experimental farm of APRC Nitra for this study. The animals were divided into two groups (first group 1P – ewes, and second group 2P – ewes). Ewes were regularly milked two times a day. Milk flow data were recorded during two evening milkings with 48 h in between. During the first measurement the half of the animals in each group was treated by 5 UI i.m. of oxytocin (OT) and the second half by physiological saline (SA) 60 s before the cluster attachment. The application of OT and SA in both groups was changed in cross-over design during the second evening milking. Milk flow kinetics were recorded individually using an electronic jar with 2-wire compact magnetostrictive level. The OT treatment caused shortening of the milking time, increasing of peak milk flow rate and milk yield in thirty seconds in both groups. There were not any changes in milk composition in 2P ewes between SA and OT treatment. In 1P ewes, there was significantly increased total milk yield, machine milk yield, peak flow rate, milk yield in thirty and in 60 s in OT treatment. Moreover, the increased fat yield was recorded in 1P group after OT treatment only. In conclusion, milk ejection occurrence before cluster attachment influences differently the milkability and milk composition in ewes differed in milk flow patterns during usual milking. Thus milk ejection is crucial in our breed for milk yield and composition recording. © 2013 Elsevier B.V. All rights reserved.
1. Introduction There are many farms in Slovakia where ewes are handmilked, though the history of machine milking is dating
∗ Corresponding author. Tel.: +421 903 546 401; fax: +421 376 546 483. E-mail address: [email protected] (V. Tanˇcin). 0921-4488/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.smallrumres.2013.03.011
back to the beginning of 1960s. However, the number of farms with machine milking or interest to milk the sheep with machine is increasing in the last decade. The analysis of milk flow curves are used for monitoring of milk ejection occurrence during machine milking (Labussière, 1988; Bruckmaier et al., 1997; Dˇzidic´ et al., 2004; Maˇcuhová et al., 2008) indicating a positive physiological response of ewes, i.e. OT release, to machine stimuli.
J. Antoniˇc et al. / Small Ruminant Research 113 (2013) 254–257
Few types of milk flow were characterized in ewes. First type (1P, one emission) represents milk flow curves with one peak of milk flow before stripping when no OT release is expected in response to milking. Second type (2P, two emissions) represents milk flow with two clearly separated milk flow peaks when endogenous OT is released. With increasing milk production, the milk ejection can occur before removal of cisternal milk and thus the second peak of milk flow is masked, i.e. plateau milk flow (PL) (Marnet et al., 1998). Also larger volume of cistern and higher production could be a reason of PL due to the limitation of teat canal even if OT is not released during milking. Recently, it was found out that the volume of residual milk of ewes with PL was higher than in 2P, suggesting that not all ewes with PL released OT or milk ejection occurred during milking (Maˇcuhová et al., 2012). In dairy practice, there is not performed any teat stimulation before the cluster is attached to the teat as it is common in dairy cows (Tanˇcin et al., 2007). Thus the parameters of milkability, especially milk flow kinetic, depend on the physiological response of ewes to machine stimulation. There were reductions of 2P milk flow curves occurrence after pre-stimulation (Bruckmaier et al., 1997). Pre-stimulation causing OT release before the cluster is attached to the teat could significantly change the parameters of milkability as it was recently found out with administration of exogenous OT (Antoniˇc et al., 2013). However, we did not test the response of ewes with different milk flow kinetic during usual milking to exogenous OT in that study. Milk distribution in the udder of ewes differs from that of a cow. In ewes, large amount of milk is stored in the cistern that is available for mechanical removal only. However, the amount of milk stored in alveoli is important for milk production and fat yield as well. Normally, machine milking causes an OT release via a neuroendocrine reflex and milk ejection. Moreover, OT release is very important to stimulate milk secretion through alveoli emptying (Zamiri et al., 2001; Silanikove et al., 2010). However, machine milking could sometimes be associated with some kind of stress causing significant reduction of milk yield as a consequence of inhibition of OT release causing 1P flow (Bruckmaier et al., 1997; Negrão and Marnet, 2003) in ewes. The important role affecting OT release is adaptation of different breeds to machine stimulation. Tsigai and Improved Valachian have been shown to have relatively high percentage of 1P and 2P milk flow patterns (Maˇcuhová et al., 2008; Tanˇcin et al., 2011; Kulinová et al., 2012). Therefore, to evaluate the milkability and milk composition of above mentioned breeds during milk recording, the milk flow patterns could be taken into account. The hypothesis was that pre-stimulation (simulated by administration of exogenous OT injection) before cluster attachment will differently influence milkability and milk composition in ewes differed in milk flow pattern (1P versus 2P) during usual milking. The goals of our investigation were to evaluate the importance of milk ejection before cluster attachment on milk flow patterns, milk composition and other parameters of milkability related to physiological response of ewes to usual milking (1P and 2P response).
255
2. Materials and methods 2.1. Animals and milking management Twenty-two adult lactating dairy ewes of 2 breeds Tsigai (TS, n = 11) and Improved Valachian (IV, n = 11) with healthy udders (on the base of visual control of mammary gland and sensory evaluation of milk) from the experimental farm of the Animal Production Research Centre in Nitra, Slovakia, were selected from the flock of 400 ewes. Ewes were selected on the basis of milk flow pattern from three consecutive previous milkings before the experiment started. They were on their 3rd–8th lactation and had similar stage of lactation (100 ± 15 days in milking). 11 ewes with 1P type (1P group: 5 TS and 6 IV ewes) and 11 ewes with 2P type (2P group: 6 TS and 5 IV ewes) of milk flow were selected for the experiment. Ewes were milked routinely twice daily at 8:00 and 20:00 h with machine stripping. Machine milking took place in a 1 × 24 low-line sideby-side milking parlour with 12 milking units by one milking technician. The milking machine was set to provide 160 pulsations per minute in a 50:50 ratio with a vacuum level of 39 kPa. During each milking the ewes received 0.1 kg per head concentrate in parlour. 2.2. Experimental procedure Experimental milkings were performed during 2 evening milkings with one evening milking in between without any treatment and milk flow recording to recover the alveolar milk volume in OT treated animals. During the first measurement, half of the animals of each group were i.m. injected with 5 IU of oxytocin (OT treatment) and the second half with physiological saline (SA treatment) 90 s before the cluster attachment. The application of OT and SA in both groups was changed in cross-over design during the second evening milking. 2.3. Samples collection and analysis Milk flow kinetics were recorded individually using an electronic jar that continuously collected the milk during milking. Within the jar there was a 2-wire compact magnetostrictive level transmitter (NIVOTRACK, NIVELCO Ipari Elektronika Rt, Budapest, Hungary) connected to a computer. The milk level in the jar was continuously measured by a transmitter that recorded the signals on a computer once per second. The registered data were processed with Microsoft Excel® . Milk flow curves were evaluated according to Bruckmaier et al. (1997), Rovai et al. (2002) and Maˇcuhová et al. (2008) into 3 types (1peak (1P), 2peaks (2P), plateau (PL)) to select the animals with 1P and 2P milk flow types as well as to record the change in response to OT treatment. The milk flow pattern was calculated using a formula by Maˇcuhová et al. (2007): Milk flow rate (L min
−1
) = (Ln − Ln−4 ) × 15,
L − milk yield in liters,
n − time in s, n > 3 s. From the measured parameters the following data were evaluated: total milk yield (TMY, L), machine milk yield (MMY, L), stripped milk yield (SMY, L), stripped milk yield (SMY, %), milking time (MT, s), peak flow rate (PFR, L min−1 ), time to peak flow rate (TPFR, s), milk yield in 30 s (MY30S, L), milk yield in 60 s (MY60S, L). After each milking, the individual milk samples were collected from the jar for composition analysis. The milk composition was analyzed for percentage of fat, protein, lactose, total solids and solids-not-fat with MilkoScan FT120 (Foss, Hillerød, Denmark). Somatic cells count (SCC) was analyzed with Somacount 150 (Bentley Instruments, Inc., Chaska, Minnesota) analyzer. Fat yield was calculated by using formula: Fat [g] =
TMY [L] × × fat [%] ; 100
= 1038 kg m
−3
2.4. Statistical analysis Totally 42 milk flow curves and 42 milk samples from 21 ewes were evaluated and analyzed by Statistica programme (version 8.0, StatSoft. Inc.). One ewe from OT treatment was removed from statistical evaluation due to no milk flow during milking. T-test of dependent samples was used for comparison of milkability parameters and milk composition between
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Table 1 Milking characteristics in ewes in one (1P) and two peaks (2P) group of milk flow in response to saline (SA) and oxytocin (OT) treatment (mean ± S.E.M.). Parameter
TMY, L MMY, L SMY, L SMYF, % MT, s PFR, L min−1 TPFR, s MY30S, L MY60S, L
1P group
2P group
S.E.M.
SA treatment
OT treatment
SA treatment
OT treatment
0.19aA 0.08aA 0.11 55.5a 44.3 0.52A 18.6 0.06A 0.07aA
0.24B 0.13B 0.11 45.9 35.5 0.78B 14.7 0.10B 0.12B
0.29b 0.18b 0.11 37.9b 54.6A 0.80A 18.8 0.09A 0.15b
0.28 0.17 0.11 38.4 27.0B 1.12B 14.9 0.14B 0.16
0.01 0.02 0.03 3.01 4.30 0.07 1.64 0.01 0.01
TMY: total milk yield; MMY: machine milk yield; SMY: stripped milk yield; SMYF: stripped milk yield fraction; MT: milking time; PFR: peak flow rate; TPFR: time to peak flow rate; MY30S: milk yield in 30 s; MY60S: milk yield in 60 s. Means in the same line with different letters are different (p ≤ 0.05). a,b Between the groups within treatment. A,B Between treatments within group.
treatments within each group. For comparison of milkability parameters and milk composition between the groups within treatment, the T-test of independent samples was applied.
3. Results After OT treatment, milk flow curves changed: from 11 ewes in 2P group, 8 ewes had 1P and 3 ewes still had 2P; from 11 ewes in 1P group, 9 ewes had 1P, 1 ewe had PL and surprisingly 1 ewe had no milk flow after the OT treatment. The characteristics and milk composition in response to SA and OT treatment in ewes with 1P and 2P type of milk flow are shown in Tables 1 and 2. TMY and MMY did not differ between treatments in 2P group. But in 1P group, TMY and MMY increased after OT treatments. On the other hand OT treatment reduced MT in 2P group. Milk components differed only in total fat yield between treatments or between groups. Fat yield was significantly lower after SA than OT treatment in 1P group and there were no differences between treatments in 2P group. There were not any other significant differences in SCC between treatments within group and between groups within treatments. 4. Discussion OT injection should compensate pre-milking stimulation, which results in the presence of alveolar milk in the cistern, before the cisternal milk is removed as pointed out
Marnet and McKusick (2001). Thus we could demonstrate different changes in milking characteristics in OT treatment milking of ewes depending on the milk flow pattern during SA milking. In both 1P and 2P groups, MT decreased and PFR increased after OT treatment indicating more effective milk removal process. But only in 1P group, milk yield increased after OT treatment, as a consequence of no OT release during SA milking. There was also a reduction of bimodal curves in 2P group after OT treatment. On the other side Bruckmaier et al. (1997) observed that pre-stimulation caused a reduction of 1P curves and an increase 2P curves when blood samples were taken. However, these changes in milk flow were caused by experimental stress during blood sampling causing the delay of oxytocin release. The fat content is higher in alveolar milk than cisternal (McKusick et al., 2002; Castillo et al., 2008; Gómez-Cortés et al., 2011) so it can be expected higher percentage of fat in 2P group than in 1P group during the SA treatment. Opposite results were found out where the numerically higher fat % in 1P versus 2P group could be ascribed to lower milk yield in 1P group because with reduction of milk yield the % of fat is increasing (Ploumi et al., 1998). On the other hand, a significantly higher fat yield in 2P group indicates the removal of alveolar milk. Therefore, due to fat distribution in the udder and the occurrence of milk ejection, there was significant increased fat yield (g) in milk after OT treatment in 1P group only. Ewes of both breeds TS and IV with 1P had significantly higher residual volume of milk than ewes with
Table 2 Milk composition in ewes in one (1P) and two peaks (2P) group of milk flow in response to saline (SA) and oxytocin (OT) treatment (mean ± S.E.M.). Parameter
Fat, % Fat yield, g Protein, % Lactose, % Solids-not-fat, % Total solids, % SCC (lnx )
1P group
2P group
S.E.M.
SA treatment
OT treatment
SA treatment
OT treatment
8.63 17.0aA 5.86 4.66 11.41 19.8 11.64
9.29 22.9B 5.82 4.68 11.39 20.4 11.75
8.31 25.2b 5.48 4.75 11.08 19.2 11.00
8.75 25.2 5.51 4.73 11.1 19.6 11.07
Means in the same line with different letters are different (p ≤ 0.05). a,b Between the groups within treatment. A,B Between treatments within group.
0.13 1.06 0.09 0.03 0.09 0.18 0.06
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2P (Maˇcuhová et al., 2012). These changes in our experimental groups were caused by removing higher amount of residual milk in 1P due to the lacking of endogenous OT effect during SA milking than in 2P group. PFR was significantly influenced by OT treatment in both 1P and 2P groups of ewes. In both groups during OT treatment it could not be observed any PL milk flow. This could be affected by low milk production, because steady state (plateau – PL) milk flow is always seen in higher yielding ewes in our conditions (Tanˇcin et al., 2011) or in other breeds (Rovai et al., 2002). PFR reduced in a course of lactation in older ewes in comparison with primiparous ewes (Casu et al., 2008) expecting larger cistern with lower intrammamary pressure. Probably the effect of OT treatment could not be so effective to increase the PFR in group of ewes with PL flow as with 1P or 2P, but additional study should be done to see the effect of exogenous OT on PFR in ewes with PL milk flow it means under higher milk production. PFR is considered as the most relevant measurement to characterize the ewes’ machine milking speed due to the high repeatability and the favourable correlation with MT (Casu et al., 2008). Thus in our breeds PFR under one or two emissions milk flows is not as exact as in ewes with PL milk flows. Under such low milk yield of our breeds with higher occurrence of 1P milk flow types we probably could not use the PFR as reasonable traits to evaluate milkability during milk recording. Also fat yield in milk from ewes with 1P milk flow does not correspond to the real situation in the udder. 5. Conclusion The milk ejection reflex induced before cluster attachment influenced parameters of milkability and milk composition depending on the physiological response of ewes to usual machine stimulation. Thus influenced parameters of milkability and milk composition could be limited for their importance in milk recording. This study contributes to the knowledge about physiological adaptability and suitability of above mentioned breeds to machine milking. Acknowledgement This study was funded by the Operational Programme for Research and Development project “CEGEZ No. 26220120042” and “MLIEKO No. 26220220098” of the European Regional Development Fund. References Antoniˇc, J., Maˇcuhová, L., Uhrinˇcat’, M., Tanˇcin, V., 2013. The effect milk ejection occurrence before or during machine milking on milkability and milk composition of ewes. Vet. Med. Zoot. 61, 3–7.
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Bruckmaier, R.M., Paul, G., Mayer, H., Schams, D., 1997. Machine milking of Ostfriesian and Lacaune dairy sheep: udder anatomy, milk ejection and milking characteristics. J. Dairy Res. 64, 163–172. Castillo, V., Such, X., Caja, G., Salama, A.A.K., Albanell, E., Casals, R., 2008. Changes in alveolar and cisternal compartments induced by milking interval in the udder of dairy ewes. J. Dairy Sci. 91, 3403–3411. Casu, S., Marie-Etancelin, C., Robert-Grani, C., Barillet, F., Carta, A., 2008. Evolution during the productive life and individual variability of milk emission at machine milking in Sardinian × Lacaune back-cross ewes. Small Rumin. Res. 75, 7–16. ´ A., Kaps, M., Bruckmaier, R.M., 2004. Machine milking of Istrian Dˇzidic, dairy crossbreed ewes: udder morphology and milking characteristics. Small Rumin. Res. 55, 183–189. Gómez-Cortés, P., Mantecón, A.R., Fuente de la, M.A., Manso, T., 2011. Milk composition and fatty acid profile of residual and available milk from ewes fed with diets supplemented with different vegetable oils. Small Rumin. Res. 97, 72–75. Kulinová, K., Maˇcuhová, L., Uhrinˇcat’, M., Tanˇcin, V., 2012. The effect of stressful treatment before and during milking on milkability of dairy ewes. Vet. Med. Zoot. 57, 39–43. Labussière, J., 1988. Review of physiological and anatomical factors influencing the milking ability of ewes and the organization of milking. Livest. Prod. Sci. 18, 253–274. Maˇcuhová, L., Tanˇcin, V., Uhrinˇcat’, M., Maˇcuhová, J., 2012. The level of udder emptying and milk flow stability in Tsigai. Improved Valachian and Lacaune ewes during machine milkings. Czech J. Anim. Sci. 57, 240–247. Maˇcuhová, L., Uhrinˇcat’, M., Maˇcuhová, J., Margetín, M., Tanˇcin, V., 2008. The first observation of milkability of the sheep breeds Tsigai. Improved Valachian and their crosses with Lacaune. Czech J. Anim. Sci. 53, 528–536. ˇ Maˇcuhová, L., Uhrinˇcat’, M., Marnet, P.G., Margetín, M., Mihina, S., Maˇcuhová, J., Tanˇcin, V., 2007. Response of ewes to machine milking: evaluation of milk flow kinetic. Slovak J. Anim. Sci. 40, 89–96 (in Slovak). Marnet, P.G., McKusick, B.C., 2001. Regulation of milk ejection and milkability in small ruminants. Livest. Prod. Sci. 70, 125–133. Marnet, P.G., Negrão, J.A., Labussière, J., 1998. Oxytocin release and milk ejection parameters during milking of dairy ewes in and out natural season of lactation. Small Rumin. Res. 28, 183–191. McKusick, B.C., Thomas, D.L., Berger, J.M., Marnet, P.G., 2002. Effect of milking interval on alveolar versus cisternal milk accumulation and milk production and composition in dairy ewes. J. Dairy Sci. 85, 2197–2206. Negrão, J.A., Marnet, P.G., 2003. Cortisol, adrenalin, noradrenalin and oxytocin release and milk yield during milkings in primiparous ewes. Small Rumin. Res. 47, 69–75. Ploumi, K., Belibasaki, S., Triantaphyllidis, G., 1998. Some factors affecting daily milk yield and composition in a flock of Chios ewes. Small Rumin. Res. 28, 89–92. Rovai, M., Such, X., Caja, G., Piedrafita, J., 2002. Milk emission during machine milking in dairy sheep. J. Anim. Sci. 80 (Suppl. 1), 5. Silanikove, N., Leitner, G., Merin, U., Prosser, C.G., 2010. Recent advances in exploiting goat’s milk: quality, safety and production aspects. Small Rumin. Res. 89, 110–124. Tanˇcin, V., Uhrinˇcat’, M., Maˇcuhová, L., Bruckmaier, R.M., 2007. Effect of pre-stimulation on milk flow pattern and distribution of milk constituents at a quarter level. Czech J. Anim. Sci. 52, 117–121. Tanˇcin, V., Maˇcuhová, L., Oravcová, M., Uhrinˇcat’, M., Kulinová, K., Roychoudhury, Sh., Marnet, P.G., 2011. Milkability assessment of Tsigai, Improved Valachian, Lacaune and F1Crossbred ewes (Tsigai × Lacaune. Improved Valachian × Lacaune) throughout lactation. Small Rumin. Res. 97, 28–34. Zamiri, M.J., Qotbi, A., Izadifard, J., 2001. Effect of daily oxytocin injection on milk yield and lactation length in sheep. Small Rumin. Res. 40, 179–185.