2021 SCIENCELINE

O nline J ournal of A nimal and F eed R esearch

Volume 11, Issue 1: 18-22; January 25, 2021

ISSN 2228-7701

DOI: https://dx.doi.org/10.51227/ojafr.2021.4

EFFECT OF LACTATION LENGTH AND LITTER SIZE ON MILK

COMPOSITION OF BOER GOAT WITHIN ONE MONTH OF

PARTURITION



Sagar REGMI¹, Premlal MAHATO¹and Khagendra Raj SAPKOTA²

¹Agriculture and Forestry University, Rampur, Chitwan, Nepal

²National Livestock Breeding Office, Pokhara, Nepal



Email: saregme@gmail.com;

: 0000-0003-1856-8780

^Supporting Information

ABSTRACT: The aim of this study was to determine the effect of lactation length and litter size on the milk

composition of Boer goats. Milk samples from 23 lactating Boer goats reared in NLBO (National Livestock

Breeding Office), Pokhara, Nepal, were collected and analyzed in a laboratory present within a farm. Goats

were reared under the same environment and provided with similar care and management. Lactation length

showed a non-significant effect on fat content in the milk whereas all other constituents were influenced

significantly. Similarly, litter size showed a significant effect on the freezing point of milk only. Litter size and

all milk constituents were negatively correlated. However, Litter size and freezing point showed moderately

strong correlation. Twinning did not significant influence fat, protein, lactose and solids nonfat content of goat

milk. All constituents were weakly correlated to litter size however freezing point showed moderately strong

correlation. Thus, more focus must be given to the nutritional management of triplets and twins to improve

their growth rate compared to a single kid.

Keywords: Boer goat, Lactation length, Milk composition, Litter size, Twinning.

INTRODUCTION

Boer goats (Capra aegagrus hircus) are one of the most desirable goat breeds with good meat conformation, short hair

and a variety of color patterns and are believed to be the result of a genetic pooling of African indigenous goats, Indians

goats, Angora goats, and European dairy goats (Lu, 2001). Boer goats were believed to be brought in Nepal around 1999

A.D. Boer goats started being reared for detailed research in Goat Research Center, Bandipur in 2008 A.D (Nepali, 2016).

Its demand has been increasing worldwide for its excellent body conformation, fast-growing rate, and good carcass quality

(Lu, 2001). Boer breed has higher immunity to diseases and quicker maturity than our local breeds. The growth rate of

Boer kids was found to be 150- 300 grams per day (Nepali, 2016). The average growth rates were also recorded as 291,

272, 245, and 250 g/day in male goats and 272, 240, 204, and 186 g/day in female goats from birth to 100, 150, 210,

and 270 days of age respectively (Lu, 2001). Multiple kids can easily be reared as it produces an adequate amount of

milk during lactation.

Two percent of the world's total annual milk supply is maintained by goats. Goat milk possesses higher digestibility

of protein and fat, alkalinity, buffering capacity, and certain therapeutic values over a cow or human milk (Park, 2009).

Goat milk has significantly higher protein and ash, but lower lactose, than human milk (Park, 2009). It can therefore be

considered as the main replacement of cow’s milk for lactose intolerant individual (Kalyankar et. al., 2016). Goat milk is

richer in caproic, caprylic, and capric acids than cow milk with 6, 8, and 10 carbon atoms, respectively (Chilliard, 1997 ). It

is composed of medium-chain fatty acids (8-12 carbon atoms) that are efficient antimicrobials (Desbois and Smith,

2010 ). Goat milk is rich in calcium and phosphorus and is consumed in many regions, such as the Middle East, southern

Asia, and some tropical countries.

Milk composition is affected by multiple factors like age, breed (Sung et al., 1999), nutrition, parity, stage of

lactation (Ciappesoni et. al., 2004 ), environment, fodder, the season of kidding (Crepaldi et. al., 1999 ), etc. The main aim

of this paper was to determine the effect of lactation length and litter size on milk constituent’s i.e. fat, lactose, Solids

Non Fat (S.NF), protein, and freezing point. Various researches have been carried out to determine the composition and

factors affecting the composition of goat milk. However, there is limited information specific to Boer goats in the

Nepalese environment during the early stage of lactation.

Citation: Regmi S, Mahato P, Sapkota KhR (2021). Effect of lactation length and litter size on milk composition of Boer goat within one month of parturition. Online J.

Anim. Feed Res., 11(1): 18-22. DOI: https://dx.doi.org/10.51227/ojafr.2021.4

MATERIALS AND METHODS

Study area

Milk samples were collected from Boer goats reared

under the intensive system in NLBO, Pokhara primarily for

research purpose and up-grading of local breed. The research

site is located within longitude 83° 58' 20.604'' E and

latitude 28° 15' 48.996'' N at an altitude of about 793m

above sea level (Figure 1). Twenty three Boer goats were

lactating at the time of data collection. These therefore

constituted the sample population. All goats were kept under

the same environmental conditions and were provided with

similar care and nutrition. Goats were fed with 600 gm of

concentrate per day. Ipil-Ipil (Leucaena leucocephala), Melia

azadirachta, Ficus semicordata, etc. and Oat (Avena sativa),

Sudan, Berseem, etc. were the major sources of fodder and

forage respectively provided to the goats.

Sample collection procedure



Goats were handled by two individuals in which one

restrains the goat while the other one performs milking

operation by hand.



The teats were washed with clean water and rubbed

with a clean towel to remove excess water.

A total of 10 ml of milk sample was collected from



both teats in a sterile container to analyze the milk

composition.

Figure 1 - Map showing livestock development farm in

Pokhara, Nepal.



The teats were cleaned again after milking was

completed.

The collected milk sample was then taken to the laboratory located within the farm. The samples were

homogenized before analysis using Akashganga Milk Analyzer, AMA-Mini-40. The data obtained were recorded and

analyzed to determine the effect of lactation length on milk constituents.

Data analysis

Data regarding the age and lactation length was obtained from the recoding system present within the farm. The

obtained data were recorded in an Excel sheet and were analyzed using IBM SPSS version 20 (Amos, 2011). The lactation

length was divided into three categories as 2^nd, 3^rd, and 4^thweek of lactation. The relation between lactation length and

milk constituents was analyzed using ANOVA test whereas an Independent sample T-test was used to determine the

relationship between litter size and milk composition.

RESULTS

Effect of lactation length on milk composition

The effects of lactation length on milk composition are shown in Table 1 . The study revealed that there was no

significant effect (p=0.232) of lactation length on the fat content of milk during the first month of lactation. The lowest fat

percent was recorded on the 4^thweek of lactation. Lactation length showed a significant effect (p=0.041) on the Solids

nonfat (S.N.F) content. Solids nonfat slightly decrease in 3^rdweek but was elevated again on 4^thweek. The freezing point

showed a significant difference (p=0.041) due to variation in lactation length. The trend in freezing point indicates a

constant decrease with increase in lactation length. A significant effect (p=0.042) of lactation length on the protein

content of milk was also recorded during our study. Protein content was reduced during the 2^nd, 3^rd, and 4^thweek of

lactation respectively. The lactose content of the milk was significantly affected (p=0.049) by lactation length. Lowest

lactose content was recorded at 3^rdweek of lactation based on our study

Effect of litter size on milk composition

Results of our study revealed that fat, S.N.F, protein, and lactose content of milk showed no significant difference

within 1 month of parturition due to variation in litter size (Table 2 ). All components are weakly correlated (negatively) to

litter size except freezing point. Goat milk from does with two kids showed slightly lower fat, protein, lactose, and S.N.F

content but insignificant compared to a goat with single kids (Table 2 ). The freezing point of milk showed significant

variation (p=0.043) with the number of kids. The freezing point was negatively correlated (r= -0.424) to litter size similar

to other milk constituents.

Citation: Regmi S, Mahato P, Sapkota KhR (2021). Effect of lactation length and litter size on milk composition of Boer goat within one month of parturition. Online J.

Anim. Feed Res., 11(1): 18-22. DOI: https://dx.doi.org/10.51227/ojafr.2021.4

Table 1 - Table showing the effect of lactation length on milk composition of Boer goats

Lactation period (in days)

7-14

15-21

22-30

p-value

Composition

Fat (%)

S.N.F (%)

5.963±1.983

10.438±0.466

0.692±0.048

3.788±0.181

5.700±0.278

6.150±1.801

9.930±0.414

0.654±0.024

3.610±0.152

5.420±0.229

4.440±1.582

10.040±0.182

0.648±0.014

3.600±0.071

5.460±0.114

0.232

0.041

0.042

0.049

Freezing point (Fp) (C)

Protein (%)

Lactose (%)

Mean ± SD ; Significant at p < 0.05

Table 2 - Table showing the effect of litter size on milk composition of Boer goats

No of kids

Correlation

coefficient (r)

-0.263

Single

Twins

p-value

Composition

Fat (%)

S.N.F (%)

6.44±2.357

10.357±0.556

0.689±0.056

3.757±0.336

5.657±0.336

5.39±1.587

10.031±0.366

0.656±0.020

3.631±0.130

5.469±0.199

0.225

0.109

0.043

0.101

0.106

-0.343

-0.424^*

Freezing point (Fp) (C)

Protein (%)

Lactose (%)

-0.350

-0.346

Mean ± SD, Significant at p < 0.05, *denotes correlation is significant at 0.05 level.

DISCUSSION

The study performed by Idamokoro et al. (2017) was in line with our findings showing that the milk composition including

fat showed no significant difference (p > 0.05) during the early, mid, and late stages of lactation. The mean fat percent of

Boer milk was calculated to be 4.7% (Mestawet et al., 2012) which was lower than the result obtained within our study.

The lower level of fat in goat milk is due to an increase in the molar percentage of propionic acid and the decline in the

molar percentage of acetic acids found in the rumen (Morand-Fehr and Sauvant, 1980 ). But some researches in goats

showed that the fat content in the milk gets slowly decreased in 30 days experimental period. The reason behind the

decrease of milk fat can be explained by the increase in the percentage of monounsaturated fatty acids with the progress

of lactation from 28.2% in colostrum to 33.0% at 30 days post-partum at the expense of polyunsaturated fatty acid which

is the main component of milk fat (Marounek et al., 2012). The average fat globule size of goat milk (3.5 µm) is

significantly smaller than that of cow milk (4.5 µm) and goat milk possesses a higher percentage of small fat globules

than that of cow milk (Knights and Garcia, 1997 ).

The average SNF content in the milk of Boer goats was observed to be 9.20±0.40% which is lower compared to our

findings (Idamokoro et al., 2017). Mean S.N.F content of Boer goat’s milk raised under the intensive and extensive system

was obtained to be 10.4 ± 6.5% and 10.7 ± 5.1% respectively (Greyling et al., 2004). The research performed by Simos et

al. (1996) explained that S.N.F content in the milk was determined by genetic factors rather than the energy intake of an

animal.

The correlation coefficient between the freezing point and lactose content in the Boer milk was obtained to be 0.930

(strongly correlated) which is in line with the finding of Janštová et al. (2019) stating that freezing point of goat milk is

influenced mainly by lactose and chlorides content in the milk. The proportion of milk constituents in a true solution

determines the freezing point of milk and whose proportion of those constituents are affected by multiple factors like

breed, the occurrence of subclinical mastitis, nutritional deficiencies, stage of lactation, water intake, thermal stress, and

seasonal variation, presence of CO2 in milk, etc. (Slaghuis, 2001 ). The freezing point of the milk helps to determine the

adulteration of water in the milk as it is the least variable component of milk in normal conditions (Zee, 1982).

Milk protein content tends to increase along with the advancement of the lactation period but this outcome didn’t

hold the truth in case of milk within a month after parturition based on the result obtained during our study (Singh, 1990 ).

Proteins are composed of different amino-acids with 0.7–1.0%N and are influenced by breed, stage of lactation, feeding,

climate, parity, season, and udder health status. Milk fat and protein content were determined mainly by the dietary

energy balance (Sauvant et al., 1987 ).

A maximum of 5.27 ± 1.05% lactose was recorded in the intensive feeding of Boer goats in week 5 which is in line

with our results (Banda et al., 1992). The highest mean daily milk lactose content (5.0 ± 0.7%) was recorded by Boer does

managed intensively (Greyling et al., 2004). Goat milk is often considered as a viable dairy option to those infants

showing allergic reactions to both cow milk and soya-based formula because of its lower lactose content for lactose

intolerant individuals. Our result was in agreement with Singh and Sengar (1979), who observed that lactose content

showed a tendency to decline as the lactation period progresses.

The study of Zamuner et al. (2020) explained that the goats with single kids produce milk with higher fat% and

protein% than goats delivering multiple kids. The subsequent decrease in milk fat, protein, lactose, and S.N.F content of

Boer goat with single, twins, and triplets was recorded respectively (Lacasse et al., 2014). Goats nursing two kids produce

Citation: Regmi S, Mahato P, Sapkota KhR (2021). Effect of lactation length and litter size on milk composition of Boer goat within one month of parturition. Online J.

Anim. Feed Res., 11(1): 18-22. DOI: https://dx.doi.org/10.51227/ojafr.2021.4

more milk (Non-significant) than a single kid (Alkass and Merkhan, 2011). Milk yield and milk composition are negatively

correlated (Simos et al., 1991). Suckling reflex post-partum and the physiological mechanism during pregnancy prepares

udder to produce more milk for does carrying multiple fetuses (Macciotta et al., 2008 ). Some contrasting theories are also

present explaining that there is no effect of litter size on milk composition (Carnicella et al., 2008). Several studies had

suggested that seasonal variations such as temperature, relative humidity, rainfall, and solar radiation/photoperiod

showed a significant effect on milk physicochemical composition (Clark and García, 2017). Mammary development and

subsequent milk production and its composition are influenced by pre-partum photoperiod in dairy cows, ewes, and does.

CONCLUSION

Lactation length showed a significant effect on lactose, solids nonfat, protein, and freezing point of milk except for fat

content in Boer goats within 1 month of parturition. Besides, litter size had a significant influence on the freezing point of

milk. Twinning did not significant influence fat, protein, lactose and solids nonfat content of goat milk. All constituents

were weakly correlated to litter size however freezing point showed moderately strong correlation. Thus, more focus must

be given to the nutritional management of triplets and twins to improve their growth rate compared to a single kid.

DECLARATIONS

Corresponding Author

E-mail: saregme@gmail.com; ORCİD: 0000-0003-1856-8780

Competing interest

We have no conflicts of interest to disclose concerning the research, authorship, and publication of this article.

Acknowledgment

The authors would like to convey our sincere gratitude to all our mentors in the National Livestock Breeding Office

(NLBO) for their continuous guidance and support during our study. We are thankful to the farm management team for

providing us with the lab facilities without which our study was impossible.

Authors’ contribution

S.Regmi performed conceptualization, methodology, analysis and writing-original draft; P.Mahato performed

conceptualization, methodology, analysis; Kh.R. Sapkota performed writing- review editing.

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Citation: Regmi S, Mahato P, Sapkota KhR (2021). Effect of lactation length and litter size on milk composition of Boer goat within one month of parturition. Online J.

Anim. Feed Res., 11(1): 18-22. DOI: https://dx.doi.org/10.51227/ojafr.2021.4