56 R. Kahn

4. In der Verbesserung der Grundfutterqualitat mit dem Zie!. eine hohe MiIchl~istung aus dem Grundfutter zu erzielen und dadurch die Kosten beim Futtermitteleinsatzje Kuh und Jahr zu senken.

EKdNOMSKI ASPEKTI PROIZVODNJE MLEKA U NEMACKOJ

R. Kahn

Rezime

Proizvodnja mleka mora ostvarivati prihoda kako bi egzisitrala u duzem periodu. Glavne polazne tacke su:

U modemizaciji postupka investiranjem kao preduslov za povecanje produktivnosti rada i obezbedivanje kvaliteta svezeg mleka; stirn u vezi moraju se povecavati stada

U povecanju prinosa mleka i smanjenju troSkova (po kg mleka).

U produzenju perioda koriScenja zivotinja odn. krava i to poboljSanjem uslova sredine sa ciIjem ostvarivanja visoke mlecnosti krave tokom proizvodnog ciklusa.

U poboljSanju kvaliteta osnovnog hraniva sa ciljem obezbedivanja visokog prinosa mleka i na taj nacin smanjiti troSkove koji se odnose na konzumiranje hrane po kravi godiSnje.

Kljucne reCi: TroSkovi, dobit, remont, troSkovi ishrane. troSkovi najma. fiksni troskovi, prinos mleka, investicije

Literatur

I. Wolf, J.:Eintluss von Reproduktion und Bewirtschaftung auf die Wirtschaftlichkeit der Milcherzeugung. Forschungsbericht, Landsforschungsanstalt fur Landwirtschaft und Fischerei Mecklenburg-Vorpommer, Institut fur Tierzucht, 1995.

2. Wissing, P.Gewinn muss sein' Neue Landwirtschaft. Heft 3, 2001. Deutscher Landwirtschaftsverlag Berlin.

3. Schleitzer. G.Auf dem Weg zur 10.000-liter-Kuh. Neue Landwirtschaft. Heft 9. 1999. Deutscher Landwirtschaftsverlag Berlin.

4. Koehn. R.UnverOffentlichtes Material, Hochschule Anhalt (FH), Abt. Bernburg 2000. 5. Koehn, R.Wirtschaftliche Aspekte fur eine zukunftsorientierte Milcherzeugung, REKASAN­

Journal, Heft 7/8, 1997.

6. Goebbel, T.Die Milchkuhherden miissen weiter wachsen. Neue Landwirtschaft. Heft 2.2001.Deutscher Landwirtschaftsverlag Berlin.

7. Statistisches lahrbuch der Land-, Forst- und Nahrungsguterwirtschaft, 2000

Biotechnology in Animal Husbandry 17 (5-6), p. 57 - 62, 2001 Publisher: Institute for Animal Husbandry Belgrade - Zemun

ISSN 1450-9156 UDC: 636.2082

EFFECTS OF LIVEWEIGHT AND DIFFERENT NELORE X HEREFORD CROSSES ON AGE AT PUBERTyl

J. O. 1. Barcellos, E. R. Prates, P.R.F. Mlihlbach, H. Ospina, ?

M. L. Bernardi, 1. Lopez-

COn/en/s: A trial was conducted to determine the age and liveweight at puberty of Bradford heifers obtained by various Nelore (N)-Hereford (H) crosses (25%N-75%H ; 37.5%N-63,5%H: 43.7%N-56.3H%; 50%N-50%H: 75%N-25%H). raised under four growth rates (kg/d): 0.5 (L: n=32), 0.75 (M; n=32), 1.00 (H: n=29) and 1.25 (VH; n=27) from weaning to puberty. Puberty was defined as estrus followed by formation of a corpus luteum. Backfat thickness (mm) at the start and at the end of the experimental period was determined by Ultrasonography. For treatments L, M. Hand VH puberty was detected. respectively. at the age of 433, 393 , 370 and 355 days (P<0.05). Heifers with higher Nelore percentage in crosses increased (P<0.05) age at puberty. The 75%N heifers reached puberty at a higher P<0.05) liveweight (347 kg) and a higher backfat thickness than the other crosses (P<0.05).

Keywords: body fat. live weight. reproductive efficiency. size.

Introduction and literature review

In a beef calf production system normally 10 to 20 % of cows are replaced yearly by heifers (Bol::e & Corah. /993) what demands selection and a replacement heifer development program based on management decisions aiming productivity and profitability.

Age and Iiveweight of heifers at puberty can be affected by breed, genetic composition, nutritional level and management (Bagley, /993), being nutrition the aspect of greatest impact on reproductive efficiency (Deutscher, /996). Since feeding represents the main production cost the knowledge of the interaction of feed availability and its forms of utilization with reproductive performance is a fundamental issue (Buckley et aI., /990).

I Introductury invitation paper submitted on the VI International Symposium "Systems of Animal Breeding and Economic of Animal Production at the Beginning of the New Millennium". October 2-5. 2001., Belgrade - uvodno predavanje po pozivu

, 1. O. 1. Barcellos. E. R. Prates, P.R.F. Mtihlbach, H. Ospina, M. L. Bernardi, 1. LOpez, Department of Animal Science - Faculty of Agronomy - Federal University do Rio Grande do Sui - Porto Alegre - RS -Brazil

58 1. O. 1. Barcellos et al.

According to various authors (Lamond, 1970; Roche & Diskin, 1995) the occurrence of a minimum liveweight associated to the chronological age of beef heifers is the main mechanism triggering the onset of puberty. Daily weight gains exceeding 0.4 kg after weaning do not affect age at puberty, since growth rate exerts a reduced effect on first estrou~'when a minimal critical weight has been attained (Schillo et aI., 1992).

Weekley et at. (1993) determined the effects of the bull ' s breed and nutritional level after weaning on the "target weight" for onset of puberty obtaining an average value of 62.7 % of mature weight. Adjusting the values for the bull's breed heifers of Simental, Senepol, Bradford, Simbrah and Brahman sires achieved, respectively, 59 .8, 61.7, 63 .2, 64.2 and 65.3 %. In this study the authors showed that heifers with 25, 44 and 56 % of Brahman crosses reach puberty, respectively, at 362, 430 and 448 days of age'.

First ovulation in young females will not happen until a critical amount of fat will accumulate as a proportion of body mass as a principle of survival and preservation of species represented by nutritional requirements for gestation and lactation (Bronson & Manning, 1991).

Besides the aspects presented above, possibly factors other than those of chronological order, such as body and gain composition, the ratio liveweight: fat content might be more important for the onset of puberty. Furthermore, studies concerning age at puberty have only presented major variations with animals submitted to undernutrition. Therefore, the knowledge of the relations of parameters such as liveweight and/or body composition with the onset of puberty in heifers aiming a precocious breeding is important to establish feeding systems based on rates of weight gain at the lowest possible production cost.

Experimental procedures

Hundred and twenty Bradford heifers with 206 ± 10 days of age and an initial weight of 184 ± 12 kg, born in the spring of 1998 and weaned in autumn of 1999, obtained by the following Nelore (N)- Hereford (H) crosses: 25%N-75%H, 37.5%N-63 .5%H, 43.7%N-56.7%H, 50 %N-50%H and 75%N-25%H , were raised under four growth rates of 0.5 (L; n=32), 0.75 (M;n=32), 1.00 (H; n=29) and 1.25 kg/day (VH; n=27) from weaning to puberty.

Table 1. Diet composition for the established weight gains Tabela 1. Sastav obroka za utvraene priraste teiine

Ingredients-sastojci L M H VH (kgDM/headJday) (0.5kg/d) (0.75kg/d) (I.Okg/d) (1.25kg/d) {kg SM/grlo/dnevno} Alfafa hay-seno lucerke 4.50 4.10 3.00 1.80 Ground corn-kukuruz 0.50 1.15 2.10 2.70 Soybean meal-sojina sa~ma 0.00 0.00 0.20 0 .80 Mineral suppl.-miner. dodaci ad lib. ad lib. ad lib. ad lib. ME - Mcal/kg DM-SM 2.27 2.39 2.59 2.82 0bserved ADG (kg/d)-

0.536±0.010 0.727±0.010 0.941 ±0.01 I 1.I54±0.011 " atran ADG (kg/d)

Effects of liveweight and different Nelore x Hereford crosses on age at puberty 59

. Experimental diets (Table I) aiming a target weight at puberty of 62 % of mature weight for the Bradford breed (Weekley, 1993) were calculated accor.ding to the NRC requirements (1996), with adjustments every 28 days, for liveweight, mature weight, breed, body condition score and local environmental conditions in order to obtain the

established daily gains.

Heifers were kept in four paddocks receiving the experimental diets from May 1st

,

1999 until January 20th , 2000. The end of the experimental period was determined by puberty onset defined by estrous activity and progesterone levels in blood higher than I ng/ml. From August 1st , 1999 on heats were detected by prepared bulls with chin-ball markers. Blood samples were collected between the 7th and loth day post estrous. Heifer's weights were registered every 28 days, following a 12 hour fasting period and during

estrous. Backfat thickness was determined by ultrasound (Aloka SD500, 3.5MHz) between

12'h and 13 th rib at each weight control and by the end of the experimental period.

Data were analyzed as a completely randomized design with a 4 x 5 factorial arrangement of treatments. Weight at puberty (BOP), age at puberty (AP) and backbit thickness (FT) were submitted to the analysis of variance for the effects of nutritional level. breeding degree and their interaction, using the LM procedure of SPSS (1999). Breeding degree (N) and backbit thickness were used as independent variables tested on age at puberty for linear and quadratic effects, adjusted to level of nutrition.

The Toukai's test was employed to compare the effects of nutritional level and the

interaction nutrition x breeding degree over BOP, AP and FT.

Results and discussion

Effects of nutritional level and breeding degree interacted significantly (Table 2) with heifers of treatments H and VHF being heavier at puberty than heifers Land M (P<0.05). However, heifers of the group 50% N showed heat with a lower body weight (303-kg) than heifers from the other breeding degrees at the lowest nutrition level (L). Possibly the effects of heterosis might have been more evident at the lowest nutritional level and expressed according to age (Table 3) and weight at puberty (Gregory et

al. . 1979). Heifers with higher Nelore crosses (50 %N and 75 % N) were heavier at first

estrous, what was more evident at the nutritional levels Hand VH. According to Weekley et al. (1993), heifers from the 56% Brahman breeding degree reached puberty later and

heavier than those from a 25 % Brahman cross.

Ages at puberty determined in this study are similar to those obtained by Cundiff et al. (1993) and Gregory et al. (1993) evaluating several crosses. Higher age at first estrous was related to higher Nelore proportion. However, nutritional level showed important effects within each breeding degree. In general, heifers of group 25 % N did not differ (P>0.05) in age at puberty with rates of weight gain higher than 0.5 kg/day. These heifers of lower body size reached puberty earlier at a lower percentage of mature weight as compared to the other breeding degrees (Freetly & Cundiff, 1997). Furthermore, this group had less differences in backfat thickness at puberty between levels M and H. In cattle differences in body composition between breeds of early and late maturity but with similar body weights suggest the existence of a direct relationship of fat proportion to onset of puberty (Bronson & Manning, 1991; Hall et aI., 1995) .

60 J. O. J. Barcellos et al.

The higher nutritional level determined a reduction of the age at puberty proportional to the increase of Nelore crosses.

With the present data the effect of backfat thickness on the age at puberty is shown in Figure I (P<0.05; r2 =0.60).

Table'2. Liveweight at puberty (kg) of beef heifers according to postweaning nutritional level and Nelore percentage

Tabela 2. Telesna tetina polno zrelih (kg) junica prema nivou ishrane nakon odbijanja i procenat nelore gena

Nutritional level! % of Nelore!!2rocenat nelore rase

Nivo ishrane 25 37.5 43.7 50 75 Mean!

Sred. vred. L 319"'\" 311,AB 306,AB 303 aB 308,AIl 309' M 292 bA 305,A 319bB 319bB 362bC 319' H 330aA 312,B 330bA 344'c 370bO 337b

VH 354'A 349bA 344'A 370dB 373 bB 358' Mean 324AB 319A 325AB 334B 353c

*- Means. wilhin a row. followed by differenl small leners are different by Tukey lesl - Srednje vrednosli unular jednog reda obele1ene malim slovima se razlikuju po Tukey leslll (P<O.05) .

•• . Means. wilhin a column. followed by different capilal leners are differenl by Tukey lesl . Srednje vrednosli unular jedne kolone obele1ene malim slovima se razlikuju po Tukey leSlU (P<O.OS).

Table 3. Age at puberty (days) of beef heifers according to postweaning nutritional level and Nelore percentage

Tabela 3. Uzrast tovnih junica u polnoj zrelosti (dana) prema nivou ishrane nakon odbijanja i procenat nelore gena

Nutritionallevell Nivo ishrane

L M H VH Mean

% ofNelore!procenat nelore rase

25 37.5 43.7 50 75

428,'1\" 433 aA 440aA -'40gw 456'c 346bA 382bB 408 bC 374bB 459,0 356bA 334'B 376'c 376bC 410bo

339bA 354 ciA 354 dA 348,A 380,B

367A 375A 394B 377A 426c

Mean! Sred. vred.

4 '" JJ

393 b

370' .... - -c J))

*- Means, within a row, followed by different small letters are different by Tukey test -Srednje vrednosti unutar jednog reda obelezene malim slovima se razlikuju po Tukey testu (P<0.05).

** - Means, within a column, followed by different capital letters are different by Tukey test - Srednje vrednosti unutar jedne kolone obeleZene malim slovima se razlikuju po Tukey testu (P<0.05).

The inclusion of backfat thickness in the model showed an associative effect with the breeding degree.

The effects of the breeding and nutritional factors on age at puberty were quite similar in this study. On the average, heifers of group VH reached puberty by 355 days of

Effects of liveweight and different Nelore x Hereford crosses on age at puberty 61

age. These results are similar to those of group 25 % N. However, the highest level of association between the factors was observed with group 75 % N, being a higher degree of correlation between age at puberty and backfat thickness.

480

~ 450 " 'C

f' 420

~ 390 :.. ~ 360 <:

330

300 I ~ 1,8 3,3 4,0 4,6

i'-

5,1

Backfat thickness, m m

Figure I. Age Puberty and blackfat thickness Slika l. U::rast u pubertetu i debljina leane slenine

Conclusion

adjusled va lues

observed values

6,0

Beef heifers managed aiming high rates of weight gain after weaning are heavier and younger at puberty. However, there is a strong association with the degree of Nelore crossing. Heifers with higher Nelore crosses are older at puberty and demand more backfat thickness when compared to crosses with lower Nelore proportions.

EFEKTI TELESNE MASE I RAZLlCITIH UKRSTANJA NELORE X HEREFORD NA SPOSOBNOST REPRODUKCIJE

1. O . J. Barcellos, E. R. Prates, P.R.F. MUhlbach, H. Ospina,

M. L. Bernardi, 1. Lopez

Rezime

Izvedeno je ispitivanja da bi se utvrdili uzrast 'i tdina, u peridou polne zrelosti, bradford junica dobijenih ukr~tanjem nelore (N)-hereford (H) (25%N-75%H; 37,5%N-63 ,5%H; 43,7%N-56,3H%; 50%N-50%H; 75%N-25%H), odgajanih u cetri rezima prirasta (kg/d): 0.5 (L; n=32), 0.75 (M; n=32), 1.00 (H; n=29) i 1.25 (VH; n=27) od odbijanja do polne zrelosti. Pubertet odn. polna zrelost je utvroena kao poceak estrusa tj formiranje corpus luteuma. Debljina leone slanine (mm) na pocetku i kraju ogleda je odreoivana metodom ultrazvucnog merenja. Za tretmane L, M, H i VH pubertet - po Ina

62 1. O. 1. Barcellos et al.

zrelost je utvrdena u uzrastu od 433, 393, 370 i 355 dana, respekti vno (P<0.05) . Kod junica sa vecim procentom nelore rase uzrast u pubertetu je bio povecan (P<0.05). Junice sa 75%N su dostizale po lnu zrelost pri vecim telesnim tezinama (P<0.05) (347 kg) i vecom debljinom ledne slanine u poredenju sa ostalim melezima (P<0.05).

Kljllcne reCi: mast, telesna tdina, efikasnost reprodukcije , velitina .

References

I. BAGLEY, c.P. Nutritional management of replacement beef hei fe rs: a review. 1. Anilll. Sci., v71, n.12, dic. p.3155-3163. 1993.

2. BOLZE, R., CORAH, L.R. Selection and Development of Replacement Heifers. Cooperati ve Extension Service, Manhattan, Kansas, C-841. 8p. 1993.

3. BRONSON, F.H., MANNING, 1.M. The energetic regulati on of ovulation : a realis tic ro le of body fa t. Biology of reproduction , v. 44, n.6 , jun, p.945-950, 1991.

4. DEUSTSCHER, G.H. Developing Repltlcement Buf Heifers (Weaning- Breed ing). B-7. Breeding & Reproduc tion. University of Nebraska Cooperative Extension . 8p. 1996.

5. BRONSON, F.H .. MANNING, J.M . The energetic regulation of ovulation : a realistic role of body fat. Biology of reproduction, v. 44, n.6, jun, p.945-950, 1991.

6. BUCKLEY, B.A. , BAKER, 1.F., DICKERSON, G.E. et al. Body composition and tissue di stri­bution from birth to 14 months of beef heifers. 1. Anim. Sci., v.68, n.12, die. P.3 1 09-3123 . 1990.

7. CUN DIFF. L.V., SZABO, F. ,GREGORY, K., et al. Breed co mpari sons from de MARC-ARS­US DA Germplasm Evaluation Program. XXV Meeting of Beef Improvemen t Federation, 26-29 may, Asheville. North Carolina, 1993.

8. FREETL Y, H.C.. CUNDIFF, L.V . Postweaning growth and reproduction characteristics of heifers sired by bulls of seven breeds and raised on different levels of nutrition. 1. Anim. Sci. v. 75. n. II, nov, p. 284 1-2851, 1997.

9. GREGORY, K.E .. LASTER, D.B. , CUNDIFF, L.V. et al. Heterosi s and breed maternal and transmitted effects in beef cattle. II. Growth rate and puberty in females. 1. Anim. Sci. v. -+7. n. 5. mai, p.I042-1053, 1979.

10. GREGORY, K. E., CUNDIFF, L.V . , KOCH, R.M. et al. Germplasm utilization in beef cattle. Beef Research. Progress Report. n.4., ARS-7I, Clay Center, p.7-19, May 1993.

II. HALL, 1.B., STAlGMILLER, R.B., BELLOWS, R.A. et. al. Body composition and metabolic profiles associated with puberty in beef heifers. 1. Anim. Sci. v.73. n. 11. nov, p.3409-3420. 1995.

12. LAMOND, D.R. The influence of undernutrition on reproduction in the cow. Amm. Breed. Abstr., v. 38, p. 359-372. 1970.

13 . NATIONAL RESEARCH COUNCIL. Nutrient Requirements of Beef Callie. 6.ed. Washington:National Academy Press. 1996. 242p.

14. ROCHE, 1.F. e DISKIN, M.G. Hormonal regulation of reproduction and interactions with nutrition in females ruminants. In: Ruminant Physiology: digestion, metabol ism. growth and reproduction. ENGELHARDT, W.V., MAREK, S.L, BREVES. G. et al. Proc. of th e 8th Iltternational Symposium on Ruminant Physiology. 1995. P.409-428.

15. SCHILLO, K.K., HALL, 1.B., HILEMAN, S.M. Effects of nutrition and season on the onset of puberty in beef heifer. 1. Anim. Sci. v.70, n.12, dic, p. 3994-4005, 1992.

16. SPSS. User's Guide: Statistics. SPSS Inc. Headquarters. Chicago. IL. 1999. 17. WEEKLEY, K.A, MARSHALL, T.T., HARGROVE, D.D. Effects of nutritional environment

on percentage of mature weight at which crossbred heifers of varyng proportion of Brahman breeding attain puberty. In: BEEF CA1TLE SHORT COURSE. , Florida, May 5,6,and 7, 1993. P. 54-59, 1993.

Biotechnology in Animal Husbandry 17 (5-6), p. 63 - 69, 2001 Publi sher: Institute for Animal Husbandry Belgrade - Zemun

ISS N 1450-9156 UDC: 6363.082 (549)

GENETIC IMPROVEMENT OF LOCAL SHEEP BREED THROUGH CROSSBREEDING WITH RAMBOUILLET FOR MUTTON AND

WOOL PRODUCTION IN SW AT VALLEY OF PAKISTAN I

M. Fatah Ullah Khan2

Abstract.· Pakistan has about 28 sheep breeds with a total population of24.1 million heads found in the country. Sheep are kept primarily for mutton production but wool and skin are secondary products. Wool , which is produced in the country is of coarse type and it is used for carpet and carpet by-products. In Swat valley; for thi s purpose from early e ighties to 1998 , pure Rambouillet rams were distributed among the farmers. To see the impact of crossbreeding under field conditions, the basic performance data of production traits were collected and analyzed statistically. The mature body weight of sheep were increased significantly (p<O.O I) from 26.40± 0.75kg to 32.20±0.20kg. The fertility rate between the two groups was not significantly (p>0.05) different 81 % Vs 85%. The lamb survival rate was higher 93% in crossbred whereas it was 84% in local sheep which was significantly higher. The significant (p<O.OI) difference was observed in wool production which increased from 0.800kg to 1.8kg per annum. The quality of wool was improved from 24.5).! to 21. I).! in local and crossbred sheep respectively. With this improvement in the sheep flocks; shepherds have the extra income of RS . 8.40 million (about 1.53 million US$) in Swat Valley.

Key Words: Genetic improvements, mutton, wool quality and quantity, Rambouillet, Pakistan.

Introduction and Literature Review

Pakistan has about 28 breeds of sheep with a total popUlation of 24.4 million heads found allover the country. Mutton is . preferred meat for most of the population; which contributes 20% of the total mutton produced in the country (GOP 1999). Wool is secondary products. But export earning from added value wool products is a major contribution to overseas earning. Domestic wool production of poor quality interim of wool yield and fiber diameter. The existing rate of growth of sheep industry does not

I Plenary inivation paper submitted on the VI International Symposium "Systems of Animal Breeding and Economic of Animal Production at the Beginning of the New Millennium", October 2-5, 2001., Belgrade - Plenamo predavanje po pozivu

l M. Fatah Ullah Khan, Animal Sciences Institute, national Agricultural Research Centre, Islamabad, Pakistan