Optimization of grazing hour for indigenous sheep of southwestern coastal region of Bangladesh

doi:10.21203/rs.3.rs-2695215/v1

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Optimization of grazing hour for indigenous sheep of southwestern coastal region of Bangladesh

https://doi.org/10.21203/rs.3.rs-2695215/v1

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The southwest coastal region of Bangladesh is at the forefront of climate change impacts. Among other components of coastal ecosystems in southwestern Bangladesh, sheep are also under threat from the effects of climate change. Therefore, the experiment was conducted to optimize the grazing time of indigenous coastal sheep in the southwestern coastal region of Bangladesh. Twenty female sheep were divided into five treatment groups before first lambing aged between 4 to 6 months and randomly allowed five different grazing periods. The experimental design was based on a randomized complete block design (RCBD). The grazing hours allocated to the five treatment groups were 4, 6, 8, 10 and 12 hours respectively. All groups of sheep were allowed to graze from 6 am to 6 pm. During this period, sheep in the special treatment group were housed when their allotted grazing period ended. All relevant information was regularly recorded in a registrar. Results showed that sheep body weight increased with increasing grazing time but the mean difference did not differ significantly. In most cases, the maximum body weight was observed in sheep grazed for 10 hours per day. The average growth rate of sheep at third and ninth weights varied significantly (p < 0.01) between sheep groups grazed 4, 6, 8, 10 and 12 hours. At third weight, the highest growth rate (g d^− 1) was 87.50 for sheep graze 10 h, followed by 12 (68.83), 8 (60.17), 6 (57.67), and 4 (39.00) hours of grazing respectively. It can be concluded that body weight and growth rate of native sheep increased with increase in grazing time. However, 10 hours of grazing meets the requirements for their maintenance and growth due to good pasture quality.

Body weight

Coastal sheep

Grazing hour

Growth rate

Performance

Livestock is a significant component of the farming system of Bangladesh as it is not only a source of protein but also an important source of farm power services as well as employment. As an agricultural country, livestock is the second most important part of Bangladesh. About 80 to 85% of the households of rural areas keep livestock (Hossain et al., 2016). The sheep population is increased 2.5 times with an annual growth rate of 5% during the last twelve years (BBS, 2008). Among all the animals, sheep play a momentous role in the national economy of Bangladesh. There are multipurpose uses of sheep including skin, wool and meat production. Sheep are distributed all over the country. Among all sheep, 32% are reared in Barind, Jamuna basin and Coastal areas of Bangladesh (Bhuiyan, 2006) and, the rest are distributed all over the country.

There are 3.401 million sheep in Bangladesh (DLS, 2017). Annually, 9.4 thousand metric tons of meats are produced from sheep. Sheep’s average live weight is about 15–25 kg (Mukherjee, 2000). Wool is produced as a byproduct which has a great demand in the world market and farmers can earn foreign currency. The total wool production of coastal sheep was reported about 853.9 g per sheep in a year (Hassan and Talukder, 2011). Among all domestic animals, sheep can exist by feeding poor quality feed resources. Under the traditional feeding system, the sheep are raised in the rural areas, coastal areas and also in-plane unproductive lands under zero input. Sheep can be allowed to graze on fallow lands, roadside, canal sides (Sultana et al., 2010), marshy lands full of aquatic weeds and also in knee-deep water without little or no concentrate supplementation. Sheep farming is very popular nowadays because of its early maturity, high disease resistance, high prolificacy, the delicacy of meat, excellent wool quality, endurance to drought and low nutrient availability. Sheep also become very popular for their wide range of adaptability to adverse climatic conditions. Optimization refers to the act of making something as good as possible. The purpose of the study is the optimization of particular grazing hours to observe the best growth and reproductive performance of the indigenous sheep of the southwest coastal region of Bangladesh. The study provides significant knowledge to the researchers, planners, field workers and personnel engaged in sheep farming in the southwest coastal region of Bangladesh. The result of the study can be helpful to the farmers and researchers in optimizing the particular grazing period in which sheep give their best performance.

Study area

This study was carried out in Agrotechnology Discipline, Khulna University, Khulna, Bangladesh. It is situated at Gollamari, Khulna, Bangladesh by the river Moyur, beside the Khulna-Satkhira highway. This area is situated under the Agro-Ecological Zone (AEZ) of the Ganges Tidal Flood Plain (Rahman et al., 2019). The research units are located on N 22.80 and E 89.53 latitude and longitude.

Experimental Design

The age of sheep ranged from 4 to 6 monthsTwenty indigenous female sheep were divided into 5 treatment groups. The experimental animals were weighed individually, blocked into five groups according to their initial live weight, and assigned at random to five different grazing hours (4, 6, 8, 10 and 12 hours). The design of this experiment was based on Randomized Complete Block Design (RCBD).

Housing of experimental sheep

Sheep were kept on slate floors (made of bamboo) and kept in separate pens. The sheep shed had proper ventilation facilities. Sheds, feeders, and water were cleaned regularly. Appropriate bio-security measures were taken to prevent disease. All sheep were dewormed with anthelmintics injection (A-mectin plus) and repeated three months later. All sheep were vaccinated against infectious diseases as shown in Table 1. Sheep were allowed to graze in the field laboratory of Agrotechnology Discipline, playground, and roadside of Khulna University campus. Sheep grazing started every day at 8 am and ended at 6 pm. Fresh drinking water was provided ad libitum to all sheep. All sheep were given the same environment and facilities except for the variation in the concentrate mixture.

Deworming and vaccination of experimental sheep

Deworming was performed using anti-helminthics injection (Amectin Plus). These injections were given immediately after purchasing the sheep and repeated after three months. All the sheep were supplied with fresh drinking water. Similar environments and facilities were provided to all sheep except the variation in grazing hours. All the sheep were kept under vaccination against infectious diseases showed in Table 1.

Table 1

Schedule of vaccination of experimental sheep
Vaccination date	Name of Vaccine	Quantity/ Sheep	Route of Vaccination
04/06/2020	FMD vaccine	2.0 ml	Sub-coetaneous
20/06/2020	Hemorrhagic septicemia vaccine	1.0 ml	Sub-coetaneous
05/07/2020	Anthrax vaccine	0.5 ml	Sub-coetaneous
22/07/2020	Sheep pox vaccine	1.0 ml	Sub-coetaneous

Grazing of experimental sheep

All the sheep were allowed to graze in naturally available pasture land around the field laboratory of Agrotechnology Discipline, roadsides of Khulna University campus. At night, they were kept confined in the shed. Everyday grazing of sheep was started at 6.00 am and ended within 6 pm. Sheep under different treatment groups were withdrawn from grazing after completion of their allocated grazing hour. A continuous grazing system was maintained in this experiment where sheep were allowed access to the same grazing area throughout the year.

Weight determination of experimental sheep

The experimental animals were weighed individually. Weights were taken every 15 days using the digital scale (50 kg capacity).

Record keeping of experimental sheep

For identification, each animal was tagged with an individual number.

Growth rate (g/d),
Age at maturity (d),
Weight at maturity (g),
Age at first lambing (days),
Litter size (number),
Birth weight of lamb (kg),
Number of services per conception,
Survivability (%) parameters were recorded in this experiment.

Data collection

All the relevant data like-

body weight,
date of onset of estrus,
deworming, vaccination and medication were recorded in a registrar regularly.

Empty body weight data were taken fortnightly in the morning before allowing them to graze. Growth rate (g day^− 1) was calculated by subtracting previous weight from present weight and divided by the number of days.

Data tabulation and analysis

There was a provision for keeping mortality data. The data were analysed using the GLM procedure of SAS version 9.1.3. Effects of grazing hour were tested by analysis of variance and DMRT was used to compare the treatment means, with a significance level considered at p < 0.05. The growth performance of lambs was estimated on average daily gain. Data was edited using Excel 2013. Data were tabulated and analysed with a descriptive statistical method by fulfilling the objectives of the study.

Bodyweight (kg/sheep)

The average body weight of indigenous sheep at fortnight intervals under different grazing hours is shown in Table 2. Results revealed that the bodyweight increased with the increasing grazing period but the mean differences were not varied significantly (p > 0.05). In most of the cases, the highest body weight was observed in sheep grazed 10 hours per day. It indicates that 10 hours of grazing per day was sufficient to support their body maintenance and growth. No significant variation in body weight of sheep allowed different grazing periods may be due to plenty of natural grasses in their grazing field. The bodyweight of grazing sheep is dependent both on the grazing period and also the quality of pasture.

Table 2

Bodyweight (kg; Mean ± SE) of indigenous coastal sheep at fortnight interval under different grazing hours
	Grazing period (hours)					P-value
	4	6	8	10	12	P-value
Initial BW	7.69 ± 1.07	7.60 ± 1.07	7.64 ± 0.72	7.57 ± 0.74	7.68 ± 0.63	1.000
Second weight	8.29 ± 0.94	8.65 ± 1.26	8.84 ± 0.76	8.75 ± 0.90	8.90 ± 0.72	0.9909
Third weight	8.87 ± 0.80	9.52 ± 1.38	9.75 ± 0.76	10.07 ± 0.84	9.93 ± 0.76	0.9067
Fourth weight	9.28 ± 0.67	9.60 ± 1.37	9.97 ± 0.73	10.44 ± 0.73	10.48 ± 0.82	0.8503
Fifth weight	9.53 ± 0.59	9.83 ± 1.35	10.22 ± 0.74	10.50 ± 0.76	10.63 ± 0.84	0.8969
Sixth weight	9.93 ± 0.53	10.23 ± 1.46	10.60 ± 0.75	11.22 ± 0.74	10.95 ± 0.89	0.8629
Seventh weight	10.31 ± 0.46	10.70 ± 1.50	10.72 ± 0.79	11.90 ± 0.95	11.43 ± 1.07	0.8048
Eighth weight	10.81 ± 0.31	11.34 ± 1.55	11.39 ± 0.66	12.39 ± 1.04	11.97 ± 1.20	0.8431
Ninth weight	11.20 ± 0.24	11.74 ± 1.55	11.90 ± 0.68	13.01 ± 1.04	12.97 ± 1.25	0.6881
^{significance level considered at p<0.05}

Growth rate (g day^− 1)

The average growth rate of indigenous sheep at fortnight interval under different grazing hours are shown in Table 3. Data from the table showed that the average growth rate of grazing sheep at third and ninth weights varied significantly (p < 0.01) among different grazing hour groups. The mean differences in other cases did not differ significantly. At third weight, the highest growth rate (g/d) was reported to be 87.50 in sheep allowed to graze 10 hours followed by 12 (68.83), 8 (60.17), 6 (57.67) and 4 (39.00) hours of grazing. Significant differences in the growth rate of sheep were also observed at ninth weight being highest in 12 hours group and lowest in 4 hours group. The growth rate of native sheep of Bangladesh during the pre-weaning period under semi-intensive conditions was reported to be 65.0g/d (Sultana et al., 2011). Zohara et al. (2014) reported daily weight gain of indigenous ewes of Bangladesh to be 21.19 and 40.95 g/d for grazing and concentrate supplemented group, respectively. Pervage et al. (2009) recorded the growth rate of indigenous coastal sheep to be 51.21g/d. Ahmed et al. (2018) found the growth rate of coastal sheep of Bangladesh to be 91.29g/d under intensive rearing conditions. The highest daily gain was observed in coastal lambs followed by Barind and Jamuna River basin lambs (Ahmed et al., 2018). Different authors (Sultana et al., 2011; Ahmed et al., 2017; Sultana et al., 2017) stated different values for a daily weight gain of Bengal lambs at 4–9 months age range. Among them, Sultana et al. (2017) found higher values from this study for daily gain (118.17-134.33 gm/day) but others studies reported much lower values might be due to differences in feed, age of the lambs and condition of the experiments.

Table 3

Growth rate (gday^− 1; Mean ± SE) of indigenous coastal sheep at fortnight interval under different grazing hours
	Grazing period (hours)					P-value
	4	6	8	10	12	P-value
Second weight	40.33 ± 11.63	70.17 ± 12.99	79.99 ± 11.92	78.83 ± 15.68	81.33 ± 13.22	0.1999
Third weight	39.00^c ± 9.75	57.67^bc ± 9.05	60.17^bc ± 2.38	87.50^a ± 4.57	68.83^ab ± 10.27	0.0089
Fourth weight	27.00 ± 10.76	5.99 ± 3.46	15.00 ± 4.66	24.66 ± 8.28	36.50 ± 12.21	0.1694
Fifth weight	16.67 ± 6.02	15.00 ± 6.96	16.83 ± 6.24	4.17 ± 1.73	9.83 ± 3.67	0.4096
Sixth weight	26.83 ± 5.09	26.83 ± 7.51	25.16 ± 14.54	48.17 ± 5.25	21.83 ± 8.95	0.2909
Seventh weight	24.83 ± 5.49	31.17 ± 19.84	8.00 ± 13.78	45.50 ± 19.41	31.83 ± 16.40	0.5822
Eighth weight	33.50 ± 11.36	42.67 ± 12.08	44.33 ± 13.42	32.50 ± 8.85	35.83 ± 10.83	0.9205
Ninth weight	26.00^b ± 6.84	26.33^b ± 4.08	34.33^b ± 10.00	41.17^b ± 3.21	66.50^a ± 10.39	0.0097

^abc mean with uncommon superscripts in a row differed significantly.

Mortality (%)

No mortality of sheep was recorded during the experimental period.

Results revealed that the bodyweight increased with the increasing of grazing period. In most of the cases, the highest body weight was observed in sheep grazed 10 hours per day. The growth rate also increased with the increasing period of grazing. It can be concluded that the body weight and growth rate of indigenous sheep increased with the increase of grazing hours. However, due to the good quality of pasture, 10 hours of grazing fulfilled their requirements for maintenance and growth.

Acknowledgement: The researchers acknowledge the financial supports provided by the Grant of Advanced Research in Education (GARE), Bangladesh Bureau of Educational Information and Statistics (BANBEIS), Ministry of Education, Government of the People’s Republic of Bangladesh, to conduct the study. We also thank all laboratory staffs of Agrotechnology Discipline, Khulna University for their technical support and assistance.

Author's contribution: All authors contributed to the study conception and design. The manuscript has been read and approved by all named authors and there are no other persons who satisfied the criteria for authorship but are not listed. The order of authors listed in the manuscript has been approved by all of us. The individual contribution of the authors is given herewith: Conceived ideas and designed experiments: Sarder Safiqul Islam; Introduction, Data collection: Sabrina Imrose; Data analysis and findings: Md. Shafiqul Islam; Writing original draft preparation: Minhazul Abedin Sun; Writing- Review and Editing, critically revised the work: Sarder Safiqul Islam and Minhazul Abedin Sun; Supervision and funding acquisition: Sarder Safiqul Islam.

Funding: I declare that this research is supported or funded by the Grant of Advanced Research in Education (GARE), Bangladesh Bureau of Educational Information and Statistics (BANBEIS), Ministry of Education, Government of the People’s Republic of Bangladesh, to conduct the study.

Availability of data and materials: I declare that the collected data are original and all the data are collected by authors.

I declare that this manuscript is original, has not been published before and is not currently being considered for publication elsewhere.

Ethics approval: The study was carried out in accordance with the Animal Ethics Council of the Life Science School of Khulna University's standards for the treatment and use of animals. I further confirm that ethical considerations of all relevant bodies have been covered in this manuscript.

Consent to participate: Not applicable

Consent for publication: Not applicable.

Conflicts of interest/Competing interest: The authors declare that there is no conflict of interests regarding the publication of this article.

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Download PDF

Version 1

posted

You are reading this latest preprint version

Optimization of grazing hour for indigenous sheep of southwestern coastal region of Bangladesh

Status:

Version 1

Abstract

Introduction

Materials and Method

Study area

Experimental Design

Housing of experimental sheep

Deworming and vaccination of experimental sheep

Grazing of experimental sheep

Weight determination of experimental sheep

Record keeping of experimental sheep

Data collection

Data tabulation and analysis

Results and Discussion

Bodyweight (kg/sheep)

Growth rate (g day^− 1)

Mortality (%)

Conclusion

Declarations

References

Status:

Version 1

Optimization of grazing hour for indigenous sheep of southwestern coastal region of Bangladesh

Status:

Version 1

Abstract

Introduction

Materials and Method

Study area

Experimental Design

Housing of experimental sheep

Deworming and vaccination of experimental sheep

Grazing of experimental sheep

Weight determination of experimental sheep

Record keeping of experimental sheep

Data collection

Data tabulation and analysis

Results and Discussion

Bodyweight (kg/sheep)

Growth rate (g day− 1)

Mortality (%)

Conclusion

Declarations

References

Status:

Version 1

Growth rate (g day^− 1)