Feeding area of silkworm and the influence of feed amount on the cocoon productivity, heredity and technological peculiarities

IPAK QURTI BOQISH MAYDONI VA OZUQA MIQDORINING PILLA MAHSULDORLIGIGA, IRSI Y VA TEXNOLOGIK XUSUSIYATLARIGA TA'SIRI

Ushbu muammolarni ijobiy hal etish uchun ipak qurti miqdorini aniqlash va boqish joylarida ipak qurti yoshiga qarab aniqlash, ushbu bazada berilgan ozuqa miqdorining o'zgarishi, kasalliklarning oldini olish va natijada ta'minlash bo'yicha tadqiqotlar o'tkazish rejalashtirilgan. belgilangan talablarga muvofiq nav navi va unumdorligi va ishlab chiqarish bo'yicha tegishli takliflar berish.

Shu sababli, ipak qurti yoshdan yoshga o'tganda, uning tanasi fiziologik jihatdan kattalashadi, shuning uchun normal ovqatlanish uchun uni kengroq oziqlantirish kerak bo'ladi. Pilla etishtirishda to'g'ri va keng ozuqa bilan ta'minlash bugungi kunning eng muhim masalasidir. Agar ushbu amaliyot etarli darajada bajarilmasa, tut barglari etarli darajada qurtlarga berilmaydi, chunki ularda ipak qurtlarini noto'g'ri oziqlantirish va ularning o'lchamlari buzilgan.

Shunday qilib, ipak qurti etishtiradigan agrotexnik davrida ozuqa maydonlarining kamligi pilla hosilini bir qutiga 34 - 44 kg pasayishiga olib kelganligi isbotlandi.

Kalit so'zlar: ipak qurti, ozuqa maydoni, ozuqa miqdori, tırtıllar bosqichi, yashovchanlik, qurtlarni ko'paytirish, pilla etishtirish, mahsuldorlik, nav navi, tut barglari.

It is known that in the decree of the President of the Republic of Uzbekistan PD-4047 dated December 4, 2018 “About further measures on supporting development of sericulture sector in the republic” prior tasks have been set on the creation of new intensive mulberry plantation, attraction of foreign investments, implementation of advanced technologies, intensive ideas and science achievements, development of the system for increasing the production of competitive silk raw materials and silk products with high additional value, at the same time, in the decree of President of the Republic of Uzbekistan PD – 4411 dated July 31, 2019 “About the further measures on the development of complete processing in sericulture sector” the further tasks have been fixed on intensification of current reforms worked out in sericulture sphere, development of the very sector and creating favorable conditions for its diversification, elaboration of cluster method of organizing production and producing best quality cocoon on the basis of increasing investment capacity for the further processing of cocoon. In order to perform aforementioned tasks successfully, it is required to manage properly egg-producing aspect of sericulture, preparing best quality eggs, implementing centralized system in silkworm rearing, right and timely liveness of silkworm eggs, and also following to the rules of silkworm rearing agro-technics and sanitary-hygiene, particularly consider the amount of feed and feeding area.

Furthermore, the body of silkworm gets bigger and bigger when it grows from age to age, and accordingly, it requires larger feeding area. Thus, the provision of proper feeding area is one of critical issues of production aspect nowadays. If this agro -technics is not fulfilled properly, the size of silkworms becomes different: large and small, due to the wrong feeding area, inefficient provision of leaves to worms and in result, silkworms cannot consume the feed equally.

As a leading specialist and scientist in sericulture U.N. Nasirillayev (1992) emphasized that an effective consumption of the feed given to silkworm depends on the surface of the beds where the silkworms are placed. The following areas are required according to worm ages for equal and proper growth of sillworms: 1 year old – 2 m2; 2 years old – 5-6 m2; 3 years old – 12-15 m2; 4 years old – 25-30 m2; 5 years old – 60- m2.

N. Akhmedov (1992) have conducted several experiments for years on the incubation process of silkworm eggs, and proved that the equal revival of eggs depends on the size of egg box and feeding area.

Most features of living organisms depends on interaction of hereditary factors and external conditions. Each animal or plant requires a special condition for its normal growth, development and improve potential capacity.

Absence of special silkworm nurseries on the farms is seriously affecting to silkworm rearing process and cocoon productivity.

Moreover, the size of silkworm rearing area has an influence on the placement of silkworm and its development, as well as, silkworm nutrition, its state and growth. If the area is of small size, with inadequate space for each worm, feed is distributed to worms in less amount, and become dirty with worm waste. Moisture hardly evaporates from silkworm body and the layers of waste leaves on the beds, and it may affect to microclimate resulting in appearance of disease causing microorganisms. When silkworms are placed dense, they impede each other creeping over one another and injuring skins with nails, also infecting the blood (hemolymph). As a result, the death rate increases, the size of cocoon gets smaller, quality and yield sharply reduce .

If the feeding area is too large, the density of silkworms gets thin, they lose appetite, develop slowly. Leaves and other rearing inventories are inefficiently used causing economical loss. That’s why, it is required to have the feeding area normal by the ages of worms and is managed on the basis of particular norm.

According to obtained results of survey, cocoon yield and quality depends on the size of feeding area. If a box of silkworm is reared in 50 m2area 50 kgs, in 70 m2area – 80 kgs of yield was obtained.

While growing age by age, the silkworms gain weight (in the period of 25 days the silkworm grows 12-13 times). Thus, with each feeding their bodies get larger and require more space in feeding area. Therefore, before giving them leaves it is important to broaden the space and to thin the dense feeding beds. When the feeding area is not enlarged as required, it causes the less leaves supply, unequal growth and different sizes of silkworms, also excessive prolongation of worm period. According to the analysis of table-1, it was obvious that the feeding area of small size (not corresponding to the norms of feeding area requirements) resulted in prolongation of worm period of silkworms in their early ages in experimental variants for 1,5-2 days more than in comparative variant, that is, in comparative variants it lasted 11,5 days extra while in experimental variants – 13 days. This indication became considerable in their older ages, so the development period of the silkworms of experimental variant prolonged 9-14 days more than in comparative variant.

It should be emphasized that there was so poor conditions in silkworm production in some silkworm rearing farm families where I especially visited to conduct a survey and observations. Because, 2,5 boxes of worms were actually being reared in the feeding area intended for a box of worms. It is pitiful that they were working hard without knowing the rearing norms and appreciating their labor. When I observed the worms, their age was different including even 5 years old ones, some worms crept up to ceiling and cocooned there. I was sorry for them that those farms were growing silkworms without initiative and enthusiasm. The ages of worms were different in one rearing nursery. Overfed silkworms had cocooned and some of them went in butterfly period earlier than in underfed worms of smaller ages. Most of silkworms were infected with watery diseases and bleeding diseases. I think that a sericulture agronomist should observe and solve this problem. By improving this case they can obtain abundant amount of best quality cocoons. This kind of cases may occur in other regions also. Aforementioned figures show that as a result of diminishing of feeding area silkworms cannot consume the leaves equally and become smaller or larger, consequently, dormancy of worms may delay causing different diseases. Furthermore, worm period prolongs to the period of hard leaves resulting in small cocooning with low quality.

Table-1

The difference of small feeding area from the comparative variant on the period of worm forming.

Variants	Ages of silkworm, by days					Total worm period (day)
	1 age	2 age	3 age	4 age	5 age
В1	4	4,5	5,5	9	12	35
В 2	4	4,5	5,5	8	11	33
В 3	4	4	5,0	7	9	29
В 4	4	4	4,5	6,5	8	27
В 5	4	3,5	3,5	5,5	7	24

The absence of special silkworm nurseries on the farms causes serious effect not only to silkworm rearing process and its productivity, but also silkworm infection with different diseases. Because these farms breed the silkworm in various facilities, barns or stores, open terrace and other such kind of places that cannot correspond to the requirements of rearing. In result of this, silkworms are infected with various diseases causing low quality cocoon and bringing economical loss. The investigations were conducted in 2013-2015 in Buka district of Tashkent region on “Uzbekistan-5”, “Uzbekistan-6” silkworm hybrids. Experiments were done in 5 variants, in the first variant the silkworms were reared in 20 m2area, in the second variant - 30 m2, in the third variant - 40 m2, in the fourth variant 50 m2, in the fifth variant (comparative) the silkworms were bred in 60 m2area.

Infected and dead silkworms were tested in the laboratory with microscope in their rearing period and the disease types were determined. The results of experiments showed that because of requirements of small aged silkworms for less feeding area, they almost were not infected with diseases. However, they were in different sizes and weak. This case means that the worms may be infected with diseases at once in their older ages. Because the bodies of old-aged silkworms get larger fast and demand more feed and feeding area as well. There are not special silkworm nurseries in some farms, that’s why, the worms are bred in small space, not thinned, where 1,5, 2 and sometimes 3 boxes of silkworm are reared in the feeding area intended for 0,5 box. Excessive number of silkworms in a limited area causes to the density of worms which creep over each other damaging the skin of other silkworm with nails. Through this damaged part of silkworm skin various bacteria can penetrate into the body and blood. The bacteria increase and develop in the blood, destroying the blood content. Consequently, the most silkworms are damaged by bleeding disease. Besides, due to little feeding space the silkworms in upper part of the bed can consume when the feed is supplied, the rest of the worms which are in the bottom part, cannot reach to feed staying inside the layers of waste leaves. As a result, these worms are infected with watery or plague diseases. If the breeder doesn’t pick up infected silkworms before giving them feed, the disease may infect other healthy worms. During the experiment the silkworms were controlled by their ages, 10 pieces of infected silkworms were picked up in each variant, tested with microscope and the disease types were determined, these data were given in table-2.

Table-2 The results of microscopic analysis of infected silkworms with diseases due to lack of enough feeding area.

Variants	Tested	Disease type and number (pcs)
		bacteria				virus	muscardine	pebrine
		plague	bleeding	watery	total	-
В	10	2	7	1	10	-	-	-
В	10	2	7	1	10	-	-	-
В	10	3	6	2	10	-	-	-
В	10	3	6	1	10	-	-	-
В	10	3	6	0	9	-	-	-

In accordance with table data, the less is the feeding area, the more silkworms are infected with bacterial diseases. During the experiments the observations showed that diminishing of feeding area space resulted in decreasing of food amount, unequal feed consumption of worms, consequently, they have different sizes, from small to larger. It causes disease infection and prolongation of worm period of silkworms, delaying of this period to boiling hot days of summer, productivity decreasing and low quality cocooning. Therefore, it is important to require from the farmers enough facilities with favorable conditions and correspondence of feeding areas to agrotechnical rules for silkworm rearing while making contract with silkworm breeders.

In its turn, aforementioned problems may seriously influence on total cocoon amount and their hereditary. The results of the research conducted on this issue have been presented in table- 3.

Table-3

The influence of feeding area and feed amount on the hereditary of reeled cocoons.

Variants	Number  of silkworms under rearing	Total   reeled cocoons		Including :
		pcs %		Thoroughbred		Sterile cocoons		Black   damaged cocoons
				Pcs	%	pcs	%	pcs	%
Variant 1	500	240	48	156	65	77	32	7	3,0
Variant 2	500	300	60	225	75	69	23	6	2,5
Variant 3	500	360	72	310	86	45	12,5	5	2,0
Variant 4	500	410	82	369	90	37	9	4	1,5
Variant 5 (comparative)	500	450	90	423	94	25	5,5	2	0,5

According to the analysis of the data given in the table, the feeding area and the amount of the feed affect strongly to the viability of silkworm, cocooning process and also heredity of cocoons. It is obvious from the obtained data that after the change of place on the base of norms of silkworm rearing agrotechnics for feeding area decrease in the amount of leaves, the number of cocoons has radically changed compared to comparative variant.

Here, the total amount of cocoon yield of the comparative variant of 60m2 feeding area constituted 90%, in 50m2 feeding area this indication was 82 %, when the silkworms were bred in 40 m2 feeding area their cocoon yield was 72%, while in 30m2 feeding area the yield showed 60% and in 20%m2 feeding area the worms gave 48% yield.

These figures reveal that diminishing of feeding area by 20- 30 m2for one box leads to decreasing of total cocoon yield by 30-422%. Besides, there was an effect to the amount of thoroughbred cocoons too, as the share of thoroughbred cocoons reduced by 19 -29 %, and accordingly, the number of sterile and black damaged cocoons increased by 20 -30 %, as well as cocoon productivity fell down.

The data of table 4 illustrates that the decrease in the amount of feed and the size of feeding area during the period of silkworm breeding led to reducing of cocoons, mass of one cocoon and cocoon yield from 1 box.

Thus, the number of cocoons of experimental variants has decreased (48 -60 %) more than in comparative variant, and also a mass of 1 piece of cocoon has radically reduced (1,421,50 gr).

Table-4

The influence of feeding area and feed amount on the productivity of cocoon.

Variants	One box ( 19 gr)	Feeding area,m2	Yield production from one box, kg	Average mass of one cocoon, gr
1	2	3	4	5
1	1 box	20	31,0	1,38
2	1 box	30	40,5	1,56
3	1 box	40	52,2	1,74
4	1 box	50	63,0	1,81
5	1         box (comparative)		74,0	1,92

Considering abovementioned data, we can say that when the silkworms were reared in comparative variant as per the requirements of feeding area and with demanded feed amount, 1- box of silkworms has yielded 62,7 kgs in 50m2 feeding area, in 40 m2 area – 52,2 kgs, in 30m2 area – 40,5 kgs and in 20 m2 area – 30,7 kgs.

So, it was proven that less feeding area than in the norm causes the decrease in cocoon yield by 34-44 kgs per a box.

While studying the impact of feeding area and feed amount of silkworm on technological properties of cocoon, we observed that it also effect negatively to cocoon reeling.

As mentioned above, in order to identify the influence of feeding area on important farm valuable traits of silkworm including cocoon reeling, cocoon production, length and thinness of cocoon fibre, and other technological properties of cocoon, we took samples of cocoons at the end of silkworm rearing process, pupa was killed and these samples were reeled, calculated their important parameters. Information on these parameters has been presented in table-5.

The data given in the table showed that the pupa of raw cocoons and technological traits of dead dry cocoons had different parameters depending on the conditions and facility where the silkworms were reared, their feeding area and feed amount. Negative impact of little sized feeding area and less amount of feed than in the norm on the technological parameters of cocoons was determined. For example, let’s see how raw silk production from the cocoon changes, which is considered one of important technological traits. When the worms are bred in the feeding area of 20-30 m2, the raw silk production of their cocoons will be equal to 38.2 - 39.4 %, while in feeding area of 60m2in control variant this indication constitutes 41.1%. Simply we can say that this indication is 3 % less than in control variant. The similar case was observed in the variant with 40m2feeding area.

Table- 5

The influence of feeding area and feed amount on technological traits of cocoon.

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1	80	45.50	560	38.20	4.88	5.17	48.25	3046	614	79.47	1.58	902
2	85	48.45	606	39.43	4.71	4.46	48.60	3190	634	81.32	1.48	9..28
3	85	54.28	609	40.02	4..54	4.27	48.83	3310	686	82.50	1.44	954
4	85	56.42	676	40.68	4..31	4.18	49.17	3343	728	82.96	1..36	972
5	85	58.64	692	41.12	4..26	4.12	49.50	3356	764	83.200	1.28	990

Cocoon fiber winding and metric number were found to be changed depending on silkworm breeding agrotechnics and its requirements. If the worms are reared in 20 -30 m2 feeding area, metric number of silk fibre was equal to 3046 -3190, continuous cocoon reeling length was 6014-6034 m, these indications as per metric number showed 3356, continuous cocoon reeling length was 764 m, and accordingly the first indication was 8.13 % more and the second indication was 23.2 % more compared to control variant. The more parameters of fibre winding of cocoons become worse, the more decreases the amount of fibre production of the cocoon under the winding.

To sum up, the rearing of silkworms in the feeding area with less space than in the norm influences seriously on technological traits of cocoons. Important technological parameters, such as cocoon fibre winding, silk production, thinness of silk fibre were observed to decrease considerably in the variants in which the feeding area made 20 -30 m2.