The effects of some factors on milk suckled by lambs
Necmettin ÜNAL
Department of Animal Breeding and Husbandry, Faculty of Veterinary Medicine, University of Ankara, Ankara.
Summary: The effects of genotype, gender, rearing type and live weight of lambs, and lactation number and udder types of ewes on milk suckled by lambs were examined. The data were obtained from 25 ewes with 29 lambs of Kıvırcık x Akkaraman First Backcrossed and 19 ewes with 23 lambs of Chios x Akkaraman First Backcrossed. Suckled milk was measured with weigh-suckle-weigh method. The effects of genotype, gender and rearing type of lambs on suckled milk were not statistically significant in all stages and overall mean of lactation. Udder types of ewes did not significantly affect the suckled milk in all stages and overall mean during lactation period, while lactation number of ewes had a significant effect on overall mean of lactation (p<0.05). The effect of lambs’ live weights on the investigated trait was important (p<0.05, p<0.01) at all stages of lactation, and highly significant (p<0.001) for the overall mean. It was concluded that significant effects of lactation number of ewes and live weight of lambs on suckled milk were observed, while the effects of genotypes, gender and rearing type of lambs, and udder type of ewes on the investigated trait were not prominent.
Key words: Lamb, milk yield, sheep, suckled milk.
Kuzular tarafından emilen süt miktarına bazı faktörlerin etkisi
Özet: Bu çalışmada kuzular tarafından emilen süt miktarına kuzunun genotipi, cinsiyeti, büyüme tipi ve canlı ağırlığı ile koyunun laktasyon sayısı ve meme tipinin etkisi incelenmiştir. Çalışmada, 25 baş Kıvırcık x Akkaraman G1 ve 19 baş Sakız x Akkaraman G1 koyun ile bunlardan doğan 29 ve 23 baş kuzu kullanılmıştır. Kuzular tarafından emilen süt miktarı Tart-Emzir-Tart yöntemi ile belirlenmiştir. Laktasyonun çeşitli dönemlerinde ve laktasyon boyunca emilen süt miktarına kuzunun genotipi, cinsiyeti ve büyüme tipi ile koyunun meme tipinin etkisi önemsiz, laktasyon sayısının etkisi ise genel ortalama için önemli (p<0.05) olmuştur. Kuzularda canlı ağırlığın etkisi laktasyonun çeşitli dönemlerinde ve laktasyon boyunca önemli (p<0.05, p<0.01, p<0.001) olmuştur. Sonuç olarak, laktasyon boyunca kuzuların emdiği ortalama süt miktarına koyunlarda laktasyon sayısı ile kuzularda canlı ağırlığın etkisi önemli, koyunlarda meme tipi ile kuzularda genotip, cinsiyet ve büyüme tipinin etkisinin önemsiz olduğu görülmüştür.
Anahtar sözcükler: Emilen süt miktarı, koyun, kuzu, süt verimi.
Introduction
Sheep are primarily useful for meat and wool production, the relative importance of each varying with the country. They are also valued for milk in the Mediterranean and Balkan regions.
Milk production of ewes in systems where meat, wool and skin are the main economic products is importance to growth of suckling offspring. From birth to weaning, the growth of lambs is depended on milk yield of the ewe. Thus, quantity of suckled milk during preweaning period directly influences growth of lamb until weaning (1, 8). Lamb live weight and ewe milk yield were highly correlated during early and middle lactation period and these correlation coefficients declined as lactation progressed (9, 11).
The findings of investigations into factors affecting milk suckled by lambs could provide an understanding on variation of lambs’ growth.
The present study had the aims of assessing the effects of genotype, gender, rearing type and live weight of lambs, and lactation number and udder types of ewes on milk suckled by lambs.
Material and Methods
The study was carried out at the Lalahan Livestock Research Institute in Ankara, Turkey. The coordinates for the area are 330 N and 400 E.
In the study, 25 ewes and their lambs (21 single and 8 twins) from Kıvırcık x Akkaraman First Backcrossed (KAB1) genotype, and also 19 ewes and their lambs (15
single and 8 twins) from Chios x Akkaraman First Backcrossed (CAB1) genotype were used. The numbers
of KAB1 and CAB1 ewes were 22 and 17 at 140th day of
lactation, and 11 and 11 at 154th day of lactation,
respectively. Because some ewes were physiologically dried off. The data were obtained from the scope of the
project on milk yield measured by different estimation methods in KAB1 and CAB1 ewes (11). The
crossbreeding studies to obtain KAB1 and CAB1 ewes
were reported in detail (10).
Ewes were managed together as a single group. The ewes were kept indoors during the winter and were on nearby grazing areas during the day after two months from birth season. Ewes were offered 400 g daily concentrate during six weeks before lambing. Daily concentrate feed per ewe was increased up to 500 g during the lactation period. The concentrate feed included 65 % of barley, 12.5 % of wheat bran, 20 % of sunflower meal, 1.5 % of limestone, 0.5 % of salt and 0.5 % of vitamins-mineral premix. The lambs were remained with their dams in individual boxes for three days after birth. Thereafter, a flock of suckling lambs and their mothers was formed. The lambs were permitted to suckle during the lactation period. Feeders were arranged to keep the lambs away from ewes’ feed but to reach their own lamb grower feed and alfalfa hay after 3 weeks of age. The mean lactation duration was approximately 150 days.
Lambing took place between 5- 20 March 2005. Lambing occurred in a building with a littered floor which had an ambient temperature. Routine lamb managements such as clipping and iodine treatment of the navel, injection of vitamin E- selenium, ear tagging were practised.
Suckled milk by lambs was measured with Weigh-Suckle-Weigh method (3). Measurements of suckled milk were initiated on the 14th day after the date of the
first lambing occurred and continued in two weeks intervals until the ewes were dried off. Therefore, absolute data of the lambs on the days investigated were calculated by using interpolation method. The weigh of lambs was measured with electronic scale with precision of 10 g.
In the study, measurements of suckled milk were performed in two suckling sessions; morning and midday sessions. At the start of morning session, lambs were separated from their dams and held in a pen. This arrangement allowed sight and smell contact between the ewe and lamb(s), but suckling was not possible. Following a 3 hours separation on morning, lambs were weighed prior to suckling and then allowed to suckle the ewes, and weighed again immediately following the suckling. Same operation was repeated for following 3 hours period on midday session. During the suckling periods, careful observation was made to assure that ewe/lamb(s) pairs were correctly paired. The differences between pre and post suckling weights on morning and midday sessions were defined as 3 hour milk consumption by the lambs. Extracted faeces and urine by lambs during suckling sessions were not took into
consideration. Udder types were determined as type I, II, III and IV (5). Type I and II have horizontally teat placements, but type II shows division between halves of udders on the contrary of type I. Type III and IV display marked division between halves while teats attach in vertically in Type IV, but fixed in a placement between vertical and horizontal direction in Type III.
Data obtained from repeated measurements on animals were analysed using General Linear Mixed Model Procedures of SPSS (2). Fixed effects of genotypes (KAB1, CAB1), gender (male, female), rearing
type (single, twin), lactation number (1, 2, 3), udder type (I, II, III, IV), separation session (morning, midday) and two-way interaction among fixed effects were included in model for 3 hours suckled milk at different days of lactation. When data of overall mean for 3 hours of suckled milk was analysed, the model mentioned above was added with the fixed effect of the lactation days. The live weight of lambs was also added the model as a covariate. The statistical significances among subgroups were determined with Duncan’s Multiple Test (12). Each lamb of twins was considered separately when suckled milk was analysed.
Results
Means of 3 hours suckled milk by lambs during different stages of lactation are presented in Table 1. No significant interactions were found in the analyses. The effects of genotype, gender and rearing type of lambs on suckled milk were not statistically significant at all stages of lactation and overall mean. There were no significant differences for milk suckled by lambs from ewes with different lactation numbers through lactation period, but significant differences for overall mean during entire lactation period (p<0.05). Udder types did not affect the investigated trait. The effect of lambs’ live weights was important (p<0.05, p<0.01) at all stages of lactation, and highly significant (p<0.001) for the overall mean.
The curves of 3 h milk suckled by lambs considering the fixed effects are shown in Figure 1 and 2. All of curves peaked around the 2nd week of lactation
except for milk suckled from ewes with udder type III, because it reached to a peak on the 4th week of lactation.
Discussion and Conclusion
The weigh-suckle-weigh method could be used for estimating milk yield of suckling lambs by measuring the amount of milk consumed after a short interval of separation (7). However, this method has limitations for estimating milk production due to its inability to accurately measure small amounts of milk consumed by young lambs, changes in lamb appetite during measurement times and ignoring urine and faecal losses between weighing (3).
CAB1 lambs were consumed more milk than KAB1
lambs during early and mid-time of lactation period, although the differences were not pronounced. Milk consumed by lambs from CAB1 and KAB1 ewes was
nearly same for overall mean during entire lactation period. It has been reported that milk production was higher with CAB1 ewes than KAB1 ewes through
lactation period (11). The data of the present study indicated that the lambs from KAB1 and CAB1 genotypes
were suckled same quantity of milk, although CAB1
ewes had higher performance than KAB1 ewes in terms
of milk yield.
There were no significant differences for milk suckled by lambs through lactation period between two genders. According to literatures (6, 10), male lambs had higher growth performance than females. That female and male lambs were similar in terms of suckling milk could be caused by eliminating of the effect of live weight on the investigated trait.
It is generally accepted and supported in the literature that ewes rearing twin lambs produce more milk than those rearing singles (3, 9). In the present study, although each lamb of twins was considered separately when suckled milk was statistically analysed,
0 50 100 150 200 250 14 28 42 56 70 84 98 112 126 140 154 Days of lactation S uc kle d m ilk ( g / 3 h ) KAB1 lambs CAB1 lambs 0 50 100 150 200 250 14 28 42 56 70 84 98 112 126 140 154 Days of lactation S uc kle d m ilk ( g / 3 h ) Male lambs Female lambs 0 50 100 150 200 250 14 28 42 56 70 84 98 112 126 140 154 Days of lactation S uc kle d milk ( g / 3 h ) Single lambs T win lambs
Figure 1. The curves of suckled milk according to genotype, gender and rearing type
Şekil 1. Emilen süt miktarının genotip, cinsiyet ve büyüme tipine göre eğrileri
Figure 2. The curves of suckled milk according to lactation number, udder type and separation session
Şekil 2. Emilen süt miktarının laktasyon sayısı, meme tipi ve ayırma zamanına göre eğrileri
0 50 100 150 200 250 14 28 42 56 70 84 98 112 126 140 154 Days of lactation S uc kle d m ilk ( g / 3 h )
First lactation ewes Second lactation ewes T hird lactation ewes
0 50 100 150 200 250 14 28 42 56 70 84 98 112 126 140 154 Days of lactation S uc kl ed m il k ( g / 3 h) Type I Type II Type III Type IV 0 50 100 150 200 250 14 28 42 56 70 84 98 112 126 140 154 Days of lactation S uc kle d milk ( g / 3 h ) Morning seperation Midday seperation
the results showed that the twin lambs were consumed milk as quantity as the single lambs.
The effect of lactation number on the milk suckled by lambs was not significant at different days of lactation, but significant for overall mean during entire lactation period (p<0.05). The lambs of ewes on two or three lactation number were suckled more milk than those of ewes on the first lactation number. This may be caused that the ewes have generally an increase in milk production from early to intermediate ages (3, 10)
The data in the Table 1 show that there was no consistent tendency for milk suckled by lambs considering udder type at different days of lactation. Lambs of ewes with udder type II was suckled milk more than lambs from the others during entire lactation, but the differences were not significant (p>0.05).
Separation session had significant effect during early lactation, and lambs consumed more milk in second separation than that of in the first separation through lactation. This may be explained that the lambs were in a needing to consume more milk in the second separation than the first separation. Live weight of lambs had significant effect on milk suckled by lambs. It is clear from the Table 1 that the quantity of milk suckled by lambs was increased with the increasing of live weight of lambs. This result may be anticipated, since heavier lambs tend to consume more milk.
The curves for suckled milk in the present study were generally decreased more rapidly between the peak point and the 56th day of lactation. The decrease in
lactation during the period of the peak point to 56th day
coincides with the lambs’ decreasing dependence on milk due to increased feed and alfalfa intake of lambs (4).
In conclusion, significant effects of lactation number of ewes and live weight of lambs on milk suckled by lambs were observed. However, there were no significant effects for genotypes, gender and rearing type of lambs and udder type of ewes on the investigated trait.
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Geliş tarihi: 06.07.2007 / Kabul tarihi: 18.01.2008
Address for correspondence Assoc. Prof. Dr. Necmettin Ünal
Department of Animal Breeding and Husbandry, Faculty of Veterinary Medicine, University of Ankara Dışkapı, Ankara, Turkey.
