Neonatal behaviour of East Friesian lambs born in open field in Argentina

Laura Simonetti, Gloria María Lynch, Mercedes Ghibaudi and Mercedes Mc Cormick

Facultad de Ciencias Agrarias, Universidad Nacional de Lomas de Zamora, Ruta 4, Km. 2, Llavallol, Buenos Aires, Argentina
simonettilaura@yahoo.com.ar

Abstract

The objective was to study the behaviour developed immediately after birth by East Friesian lambs born in open field in Argentina. The births of 35 lambs, occurring in open land, were actually seen and their behaviours were recorded by videotape for up to 2 h in order to determine latency to each event. Once lambs have sucked, their sex, litter size and weight were registered. Females were faster in shaking head (p<0.05) and tended to attempt to stand (p<0.10), stand (p<0.10), stand firmly (p<0.10) and reach the udder (p<0.10) sooner than males. However, they finally sucked at a similar time than males (p>0.10). The unique latency affected by litter size was sucking, which tended to result shorter in twins only if birth weight was fitted in the model as covariate (p<0.10). Sucking was related to birth weight through an equation that included the quadratic term. Positive correlations were detected among all intermediate events (from attempt to stand to shake body) (p<0.01). Attempt to suck and suck positively correlated between themselves (p<0.01) but not with the other events (p>0.10).

Key words: birth weight, dairy sheep, ethology, litter size, newborn, sex

Introduction

In Argentina, sheep production is mainly developed under extensive conditions. One of the breeds used, although not widespread, is East Friesian (Ostfriesisches Milchschaff), a milk-purpose breed originated in Germany, which was introduced to our country for meat crossbreeding due to its reproductive traits (fertility, prolificacy, maternal behaviour) (Müeller 2005; Viarural 2016). Nowadays it is mainly exploited in dairy farms due to its high milk production (Suarez and Busetti 2009).

Actually, dairy sheep is seen in our country as an alternative to improve the profitability of farms, especially family oriented small scale ones, thus contributing to rural development. In such farms, dairy ewes are mostly kept under a mixed management system, where they are milked once a day in the morning and then jointed with their lambs for sucking until they are separated again in the afternoon (Suarez and Busetti 2009). In such systems, while milk and its by-products represent the main farm income, the contribution of meat production (weaned lambs) is also significant (Simonetti et al 2014).

In any system, lamb survival is essential whether to increase lamb production for sale (for meat or reproduction), to enhance the availability of ewe hoggets for selection, or to increase the flock size. The majority of lamb deaths occur in the neonatal period (within the first 72 h after birth), being the starvation-mismothering-exposure complex the main cause of these loses (Lynch 2013; Plush et al 2016).

Newborn, during and immediately after birth, experiments physiological changes, that enables it to survive in the new environment. One of the most important changes is the transition from a placental transfer of nutrients to oral ingestion of milk. Lamb needs colostrum shortly after birth as the unique source of energy and immunoglobulin (Kilpi 2015; Nowak and Poindron 2006). Besides its immunological and nutritional importance, immediate sucking also contributes to the ewe-lamb initial relationship (Nowak and Poindron 2006).

After birth, vocalization between newborn and ewe is important to develop a mutual vocal recognition. Lamb bleating plays the role of signal, and its intensity appears to be related with the breed (Dwyer et al 1998). The lamb displays its first movements, which consist in lifting and shaking the head. Then, generally leaning on the breastbone, extends its hind legs to try to stand, following by extending the four legs and finally standing up firmly (Irarí Brozia 2014). This behaviour can be displayed faster or slower by different lambs, but most of them are able to stand firmly on its four legs within the first hour of life (Irarí Brozia 2014). Having risen, the lamb is guided by visual and sonorous cues towards the ewe. Once beside its mother, it begins to search for the udder, moving its head from cranial to caudal of the ewe, attracted by the heat emitted by the udder and the smell of inguinal glands secretions. The lamb reaches the teat making munching movements and after some attempts it finally sucks (Irarí Brozia 2014).

The fastest the lamb stands and sucks its survival chances will increase (Cloete et al 2002), especially in open field parturitions where influence of weather uses to be determinant. The development of these patterns of behaviour may be affected by factors such as birth weight (Dwyer 2003; Dwyer et al 2005), litter size (Cloete et al 2002; Dwyer 2003; Dwyer et al 2005) and sex (Cloete and Scholtz 1998; Dwyer and Lawrence 1998; Dwyer et al 2005), with differences due to genotype (Darwish et al 2010; Dwyer 2003; Dwyer and Lawrence 1999, 1998; Dwyer et al 2005; Fahmy et al 1997; Irarí Brozia 2014) among others.

East Friesian ewes are mostly exploited under intensive systems in Germany, where milk is completely intended for milking, and lambs are reared artificially since birth. In such conditions, the importance of lamb-ewe bound is negligible. So, information about ewe-lamb behaviour in this breed exploited under extensive conditions, with lambs staying with their mothers, is scare.

The aim was to study the behaviour developed immediately after birth by East Friesian lambs, born in open field in Argentina.

Materials and methods

Study area

The study was carried out in a dairy sheep farm located in Uribelarrea (35º 06' S and 58º 53' W), Buenos Aires province, Argentina. The area is characterized by an annual rainfall of about 1100 mm and an average daily temperature ranging from 12ºC in July to 24ºC in January.

Animals and management

During the autumn breeding season, East Friesian ewes weighing approximately 60 kg were synchronized and mated with rams of their same breed. Throughout the year, animals were managed altogether and maintained in good health. They were kept under natural field conditions and fed good quality grasses composed of implanted (Avena sativa, Sorghum bicolor L. Moench) and native pastures ( Trifolium repens, Lolium multiflorum, Lotus tenuis). During the last month of gestation, ewes were placed on an extensive paddock and supplemented with a ration of 16% protein.

Data collection

During the daylight hours of the expected parturition dates (August), at least one observer was assigned to walk continuously throughout the paddock in order to identify ewes close to give birth. The lamb, once born, was allowed to display all behavioural events until sucking without assistance. In case a lamb was not able to suck within 2 h from birth, it was assisted.

The births of 35 lambs were actually seen and their behaviours were recorded by videotape during the first 2 h of life. The definition of each behavioural event was based on the literature (Bareham 1976; Dwyer 2003), being as follows:

- Shake head: shakes the head while being lying.

- Shake body: shakes the body while being upright.

- Bleat: vocalizes.

- Attempt to stand: puts at least one foot on the ground, with some part of the body raised from the ground.

- Stand: uprights on all four legs.

- Stand firmly: uprights on all four legs for at least 10 s.

- Nudge: actively contacts with the ewe by nosing, nudging or bunting at her.

- Look for the teat: stands in parallel reverse position, with its head in udder region.

- Attempt to suck: has teat in the mouth for lower than 10 s.

- Suck: has teat in the mouth and appears to be sucking for at least 10 s.

Once lambs have successfully sucked they were weighed with an electronic balance accurate to within 0.01 kg. Additionally, the litter size (single or twin) and the sex (female or male) of each lamb were determined.

Statistical analysis

The percentage of lambs that effectively performed each pattern with respect to the total under observation was calculated. The latency from birth to the first occurrence of each behavioural event, for those lambs that were able to suck, was recorded and expressed in minutes. Data did not meet the assumptions of parametric statistics, e.g. lack of normality. Therefore, they were analyzed by the GENMOD procedure of SAS with the gamma distribution of the experimental error and the logit function link. In a first model, sex, litter size and the interaction sex*litter size were fitted, while in a second model birth weight was also included as covariate.

The effect of sex and litter size and its interaction on birth weight, variable normally distributed, was analyzed by the GLM procedure of SAS. In all cases the interaction, due to its non-significant effect, was eliminated from the final models.

The relationships among all events were estimated by Spearman rank correlation test.

The effect of birth weight on the time spent to suck was adjusted by non-parametric regression, testing the polynomial degree by sequential sum of squares (type I) of the GENMOD procedure. Predicted values of the model and their respective confidence intervals were calculated. Regressions for the other events were not taken as valid due to the existence of influential points, so they are not informed herein.

Results

The percentage of newborn lambs that effectively performed each activity is shown in Table 1. As seen, all the lambs were competent to shake head, attempt to stand, stand and nudge, but some of them were not able to comply the other patterns. For instance, 4 lambs failed to suck unaided within their first 2 hours of life. The first activity of the newborn lambs was head shaking while being lying, which occurred immediately after birth (4.50 sec). Moreover, most of the lambs performed such activity before complete expulsion. Although in average the second event was bleating, occurring 1.30 min after birth, 13.8% of the lambs bleated after attempting to stand. The first intention to stand, registered 5.22 min after expulsion, comprised generally putting two legs on the ground (attempt to stand); however some of the lambs (22.6%) were able to directly upright on all four legs (stand). Similarly, the majority of the lambs stood firmly (9.20 min) soon after standing (5.70 min), with exception of 32.2% in which stand and stand firmly coincided. Lamb active search for contacting its mother (nudge, latency of 6.28 min) took place either after (54.8%) or before (45.2%) standing firmly. Indeed, 19.4% of the lambs were able to nudge before attempting to stand, by crawling on the ground. The lambs looked for the teat approximately 15.4 min after birth; however they took much longer to attempt to suck (33.2 min) and to ultimately suck, which was accomplished at 37.8 min (range 17.7 to 80.9 min).

Birth weight averaged 4.80±0.110 kg and was related to time to suck (Figure 1) by the equation: suck = 14.9 - 4.57*birth weight + 0.459*birth weight*birth weight (p<0.05).

The chronology of behavioural development in lambs discriminated by sex and litter size is detailed in Table 2. This table shows information for the models excluding and including birth weight as covariate. Current results show that the females tended to be faster than the males in the expression of various events. Indeed, they took less time in shaking head (p<0.05) and tended to attemp to stand (p<0.10), stand (p<0.10), stand firmly (p<0.10) and reach the udder (p<0.10) earliest. However, they finally tended to suck at a similar time than males (p=0.984).

Although the behaviour before sucking seemed to develop faster in singles than twins, differences failed to reach significance (p>0.10). Contrastly, time to suck was 23% shorter in twins than singles, being this difference again non-significant (p>0.10). However, when birth weight was fitted in the model as covariate, twins tended to first suck 33% faster than singles (p<0.10). That is, if twins were as heavy as singles, then would have sucked 13 min earlier than singles (twins: 38.8±0.0870 min vs. singles: 51.9±0.149 min). Indeed, twins weighted 4.62±0.121 kg at birth, lower than the 5.25±0.193 kg of singles (p<0.01).

Correlations among pair-wised behavioural events are shown in Table 3. As it can be noted, those behaviours developed immediately after birth (shake head and bleat) did not relate with the other events (p>0.10). Contrary, significant positive correlations were detected among all intermediate events (from attempt to stand to shake body) (p<0.01). Finally, the two latest behaviours, namely attempt to suck and suck, positively correlated between themselves (p<0.01) but not with the other events.

Figure 1. Relationship between time to suck and birth weight of East Friesian lambs

Discussion

The incidence of sucking registered in East Friesian lambs is similar to the 84.8% found in Corriedale ones in our previous report (Simonetti et al 2009), but higher than the 66% reported for Suffolk (Dwyer et al 1996) and the 44 to 68.5% of two breeds selected for terminal sire traits (Dwyer and Bünger 2012). The influence of lamb breed on sucking success has been reported by several authors (Cloete et al 1998; Dwyer 2003; Dwyer and Bünger 2012; Dwyer et al 1996). Dwyer and Bünger (2012) stated that it could be related to selection for particular traits, or to the increased human delivery assistance required by some breeds.

The latencies described herein seem to occur somewhat quicker than those recently informed (Irarí Brozia 2014) for lambs of the same breed, where they took about 8 min to attempt to stand, 14 min to effectively stand and 48 min to suck. Moreover, all activities registered herein took place earlier than those informed in our previous report in Corriedale, e.g. Corriedale lambs looked for the teat and effectively sucked 29 and 60.5 min after birth, respectively (Simonetti et al 2009). On the other hand, a shorter latency to suck has been reported for crossbred Finnish lambs, averaging 28 min (Darwish et al 2010). There is considerable evidence about the variability of lambs of different breeds/lines in the development of their activities immediately after birth (Afolayan et al 2008; Darwish et al 2010; Dwyer 2003; Dwyer and Lawrance 1999, 1998; Irarí Brozia 2014), suggesting that neonatal behaviour might be also controlled by gene action (Cloete and Scholtz 1998). In addition to the racial factor, the experimental conditions might explain some of these discrepancies. For instance, works performed indoors (Dwyer and Lawrence 1998), where the influence of climate is negligible vs. studies under extensive conditions (such as in the present study), where climate is determinant (Mormeneo et al 2006). Recently, Gronqvist et al (2015) informed failures of lambs to stand when their mothers were raised on a pasture of low availability, a common situation in extensive sheep production systems.

The inclusion of the quadratic term in the equation that relates sucking with birth weight indicates that both lighter and heavier lambs took longer to suck, although in heavier ones the relationship seemed to be more variable. Similarly, other authors reported that such relation was not linear (Cloete et al 2002; Dwyer et al 2003). As it has been postulated, the extension of labour to deliver a lamb with high weight would cause damage to the central nervous system (Haughey 1993) with consequences on neonatal behaviour (Haughey 1980). On the other hand, intrauterine growth retardation by placental insufficiency or restriction of nutrition in the pregnant mother, with the birth of lighter lambs, could also affect neonatal behaviour through neuro-developmental processes and/or physical maturation (Osgerby et al 2002). The effect of birth weight on the activities of the lambs seems to depend on the genotype. In this regard, an increase in the weight of Suffolk lambs was associated with a delay in standing, finding the udder and sucking, while this delay was only observed for sucking in Blackface lambs (Dwyer 2003).

Information from the literature suggests that neonatal behaviour of females evolutions either more accelerated for many (Dwyer and Lawrence 1998) or few events (Cloete and Scholtz 1998; Dwyer et al 2005), or at least similarly to males (Cloete et al 2002; Dwyer and Lawrence 1999; Miller et al 2010; Simitzis et al 2016). Exceptionally, Irarí Brozia (2014) found that males of 6 biotypes (including East Friesian pure and crossed) were able to stand firmly and suck (when corrected by birth weight) in average faster than females, with no differences due to sex for the other landmarks. Based on Dwyer (2003), the influence of sex seems to depend on the breed; this author found that male Suffolk lambs were slower than females to stand, attempt to suck and suck; however, there was no effect of sex in Blackface lambs, except for a tendency for males to be slower to play than females. Dwyer (2003) stated that males use to be skeletally larger and/or heavier at birth than females, factors that could increase assistance for delivery in males. As has been postulated, the extension of labour could affect the thermoregulation and the development of the neonate activities (Haughey 1980). Recently, Simitzis et al (2016) suggest that lambs with taller legs could have more difficult to stand due to such morphologic characteristic itself. Regarding to birth assistance required in the present study, its incidence in males (31.5%) seemed not to be much different to females (25.0%). Moreover, the influence of sex found in the present study would not be explained through birth weight since statistical differences were maintained when birth weight was included as covariate in the model. Indeed, sex had no influence on birth weight (females: 4.95±0.173 kg vs. males: 4.92±0.134 kg; p>0.10), agreeing with a previous report in this breed (Irarí Brozia 2014). Unfortunately body dimensions of lambs, which could affect not only extension of labour and locomotion itself, but also corporal surface directly related with thermoregulation (Irazoqui et al 1993), were not measured herein. In addition, Orgeur (1995) hypothesized that the influence of sex could be controlled by a prenatal mechanism, although Dwyer and Bünger (2012) suggested that this would occur only in breeds that have been intensively selected for production traits.

From the finding that twins tended to suck sooner than singles, it could be argued that twins might stimulate each other during the process from looking for the teat to effectively suck, probably due to visual cues between them. The literature is contradictive about the influence of litter size on lamb behaviour during the immediate postpartum. For some authors there were no differences in all neonatal behaviours between singles and twins of non dairy breeds (Blackface and Suffolk: Dwyer 2003 and Dwyer and Lawrence 1998; fine- wool Merino: Miller et al 2010). A recent report in Greek dairy breeds (Simitzis et al 2016) found that times to stand, walk and reach the udder were not influenced by litter size (singles and twins). The study of Irarí Brozia (2014), including East Friesian pure and crossed, informed that twins were as faster as singles in their earlier patterns (attempt to stand and stand firmly), however their later behaviours (attempt to suck and suck) occurred at a slower speed, being birth weight responsible for the retarded latency to suck, but not to attempting to suck; indeed, time to effectively suck was similar for singles and twins when using birth weight as covariate. The impact of litter size on behaviour seems to increase in breeds carrying more than two lambs (Dwyer 2003; Dwyer et al 2005). In this sense, Dwyer et al (2005) argued that the retarded pattern observed in triplets was besides their lower birth weight and probably related to hypoxia and placental insufficiency which would affect neural development. These authors found that triplets had a lower rectal temperature that suggests a poor thermoregulation probably due to an altered neurological development as a result of placental insufficiency.

Information from the literature on behavioural correlations is scarce. The relationship between the interval birth-stand and stand-suck was analyzed in lambs of different breeds, resulting in a positive correlation in Romanov, but not in Finnsheep or Suffolk (Fahmy et al 1997).

Conclusion

• All East Friesian lambs born in open field were able to shake head, attempt to stand, stand and nudge; however, some of them could not comply the other behavioural patterns.
  
  
• Intermediate events of their neonatal behaviour depended on sex, while the ultimate one, sucking, was affected by litter size.
  
  
• Sucking was related with birth weight through a quadratic equation.
  
  
• The first two behaviours (shake head and bleat) did not relate with the other events. Contrary, positive correlations were detected among all intermediate events. The two latest behaviours (attempt to suck and suck) positively correlated between themselves but not with the other events.

Acknowledgement

This research was financially supported by Universidad Nacional de Lomas de Zamora, Argentina (Grant: LomasCyT)

References

Afolayan R A, Fogarty N M, Gilmour A R, Ingham V M, Gaunt G M and Cummins L J 2008 Reproductive performance and genetic parameters in first cross ewes from different maternal genotypes. J Anim Sci 86:804-814

Bareham J R 1976 The behaviour of lambs on the first day after birth. Br Vet J 2:132-152

Cloete S W P and Scholtz A J 1998 Lamb survival in relation to lambing and neonatal behaviour in medium wool Merino lines diver-gently selected for multiple rearing ability. Aust J Exp Agric 38:801-811

Cloete S W P, Scholtz A J, Gilmour A R and Olivier J J 2002 Genetic and environmental effects on lambing and neonatal behaviour of Dormer and SA Mutton Merino lambs. Livst Prod Sci 78:183-193

Cloete S W P, Scholtz A J and Ten Hoope J M 1998 A note on separation from one or more lamb(s) in Merino lines divergently selected for ewe multiple rearing ability. Appl Anim Behav Sci 58:189-195

Darwish R A, Abou-Ismail U A and El-Kholya S Z 2010 Differences in post-parturient behaviour lamb performance and survival rate between purebred Egyptian Rahmani and its crossbred Finnish ewes. Small Rumin Res 89:57–61

Dwyer C M 2003 Behavioural development in the neonatal lamb: effect of maternal and birth-ralated factors. Theriogenology 59:1027-1050

Dwyer C M and Bünger L 2012 Factors affecting dystocia and offspring vigour in different sheep genotypes. Prev Vet Med 103:257-64

Dwyer C M and Laurence A B 1999 Does the behaviour of the neonate influence the expression of maternal behaviour in sheep?. Behaviour 136:367-389

Dwyer C M and Lawrence A B 1998 Variability in the expression of maternal behaviour in primiparous sheep: effects of genotype and litter size. Appl Anim Behav Sci 58:311-330

Dwyer C M, Calvert S K, Farish M, Donbavand J and Pickup H E 2005 Breed litter and parity effects on placental weight and placentome number and consequences for the neonatal behaviour of the lamb. Theriogenology 63:1092-110

Dwyer C M, Lawrence A B, Bishop S C and Lewis M 2003 Ewe-lamb bonding behaviours at birth are affected by maternal undernutrition in pregnancy. Brit J Nutr 89:123-136

Dwyer C M, McLean K A, Deams L A, Chirnside J, Calvert S K and Lawrence A B 1998 Vocalizations between mother and young in sheep: effects of breed and maternal experience. Appl Anim Behav Sci 58:105-119

Dwyer C M, Lawrence A B, Brown H E and Simm G 1996 Effect of ewe and lamb genotype on gestation length lambing ease and neonatal behaviour of lambs. Reprod Fertil Dev 8:1123-1129

Fahmy M H, Robert S and Castonguay F 1997 Ewe and lamb behavior at parturition in prolific and non-prolific sheep. Can J Anim Sci 77:9-15

Gronqvist G V, Hickson R E, Corner-Thomas R A, Kenyon P R, Stafford K J and Morris S T 2015 The effect of ewe nutrition and body condition score during very late pregnancy and the perinatal period on the behaviour of twin-bearing ewes and their lambs. Proc New Zeal Soc Anim Prod 75:219-222

Haughey K G 1993 Perinatal lamb mortality: its investigation causes and control. Ir Vet J 46:9-28

Haughey K G 1980 The effect of birth injury to the foetal nervous system on the survival and feeding behaviour of lambs. In: Wodzicka-Tomasczewska M, Edey TN, Lynch JJ (Eds) Reviews in Rural Science Armindale: University of New England pp 109-111

Irari Brozia N 2014 Caracterización al parto de 6 biotipos ovinos del proyecto ovinos prolíficos en Uruguay. Doctoral Thesis Universidad de la República Facultad de Veterinaria Montevideo Uruguay

Irazoqui H, Rodríguez Iglesias R M, Latimori N J and Giglioli C 1993 Balance térmico al nacimiento y mortalidad por inanición e hipotermia en corderos del sur oeste bonaerense. Rev Arg Prod Anim 13:183-190

Kilpi A J 2015 Serum concentrations of globulins albumin and serum amyloid a of neonatal lambs and associations with weight gain during summer rearing period. Graduation Thesis in Veterinary Medicine Estonian University of Life Sciences Institute of Veterinary Medicine and Animal Sciences Tartu Estonia

Lynch G M 2013 Efecto de la esquila preparto sobre la mortalidad neonatal en ovinos. MSc Thesis Universidad Nacional del Sur Buenos Aires Argentina

Miller D R, Blache D, Jackson R B, Downie E F and Roche J R 2010 Metabolic maturity at birth and neonate lamb survival: Association among maternal factors litter size lamb birth weight and plasma metabolic and endocrine factors on survival and behavior. J Anim Sci 88:581–592

Mormeneo I, Lynch G, Rodríguez Iglesia R M and Pevsner D 2006 Enfriamniento y muerte en corderos recién nacidos Influencia del ambiente atmosférico. Proc XI Reunión Argentina de Agrometeorología: La Agrometeorología y el Desarrollo Local Argentina pp 99-100

Müeller J 2005 Síntesis de las razas ovinas y su uso en la Argentina. In: VII Curso de Actualización Ovina INTA Bariloche Río Negro Argentina pp 3-13

Nowak R and Poindron P 2006 From birth to colostrum: early steps leading to lamb survival. Reprod Nutr Dev 46:431-446

Orgeur P 1995 Sexual play behaviour of lambs androgenised in utero. Physiol Behav 57:185-187

Osberby J C, Wathes D C, Howard D and Gadd T S 2002 The effect of maternal undernutrition on ovine fetal growth. J Endocrin 173:131-141

Plush K J, Brien F D, Hebart M L and Hynd P I 2016 Thermogenesis and physiological maturity in neonatal lambs: a unifying concept in lamb survival. Anim Prod Sci 56:736-745

SAS Institute Inc 2017 SAS/STAT Software Cary NC USA

Simitzis P, Galani K, Vasiliou P, Koutsouli P and Bizelis I 2016 Effect of breed and litter size on the display of maternal perinatal and offspring postnatal behavior in dairy sheep. J Vet Behav 13:10-18

Simonetti L, Lynch G M, Arzubi A and Mc Cormick M 2014 Resultado económico de un tambo ovino y quesería de escala familiar situado en la provincia de Buenos Aires. Proc XXXVII Congreso Argentino de Producción Animal Rev Arg Prod Anim 34: 230

Simonetti L, Lynch G M, Ganchegui M, Mormeneo I and Rodríguez Iglesias R M 2009 Pautas de comportamiento en corderos Corriedale durante sus primeras horas de vida: influencia del peso al nacer y de las condiciones climáticas. Proc VI Congreso de la Asociación Latinoamericana de Especialistas en Pequeños Rumiantes y Camélidos Sudamericanos (ALEPRyCS) Querétaro México pp 472-476

Suarez H V and Busetti M R 2009 Encuesta descriptiva sobre prácticas de ordeño manejo y producción en el tambo ovino. Vet Arg 26, wwwveterinariargentinacom/revista/2009/08/encuesta-descriptiva-sobre-practicas-de- ordeño-manejo-y-producción-en-el-tambo-ovino Last access: December 2016

Viarural 2016 wwwviaruralcomar/viaruralcomar/ganaderia/asociaciones/frisonas/ Accessed 18 September, 2017

Received 26 October 2017; Accepted 31 January 2018; Published 1 March 2018

Go to top