Section 111- Animal Feeding and Production

SECTION III: ANIMAL FEEDING AND PRODUCTION

SHEEP PASTURE MANAGEMENT AND FEEDING SYSTEMS IN THE SOUTHERN REGION OF BRAZIL

Cesar Henrique Espirito Candal Poli'; Paulo Cesar de Faccio Carvalho' ; Aida Lucia Gomes Monteir03; Felipe Jochims2; Diego Bittencourt de David2; Sergio Rodrigo Fernandes 4; Vivian

Fischer'

'UFRGS - Brazil ; 2UFRGS - Post-graduate Student; 3UFPR - Lecturer; 4UFPR - Post-graduate Student. cesar.poli@ufrgs.br .

KEYWORDS: ewe, lamb, pasture height, management tools , production system

INTRODUCTION

The sheep industry plays an important role in the production systems of Rio Grande

do Sui (RS), the most southern state of Brazil. In this reg ion, sheep production is

based on the Pampa Biome (Brazilian biome classification, IBGE 2004). Currently,

RS has the largest sheep population in Brazil, with a herd of approximately 3.8

million animals (IBGE 2004).

Historically, the sheep industry in southern Brazil is an enterprise with low

technological input, underutilizing the pasture as a source of food and favoring

parasite infection. Research for new production technologies, whilst at the same time

preserving the environrDent, began in 1999 with an important project on pasture

management for sheep. Later research was broadened to investigate different lamb , ~

production systems for meat. These studies were mainly carried out by the Federal

Universities of Rio Grande do Sui (UFRGS) and Parana (UFPR) and will be

preseQted below.

SHEEP PASTURE MANAGEMENT

Management of cultivated pasture In 1999, a research project was set up to examine sheep pasture management,

which compared the performance of lambs grazing pastures maintained at different

heights. Silveira (2002) and Pontes et al. (2004) reared yearling lambs on annual

ryegrass swards maintained at different heights (5, 10, 15 and 20 cm). These studies

~ showed average daily live-weight gains per lamb of 113 to 235 g (ADG) , and

producti~n per hectare of 240 to 662 kg (LWG/ha) (Figure 1). Maximum production

occurred between 10 and 15 cm high (Silvei ra, 2002). It was noted also that after a

certain pasture height the animal performance decreased .

'"' , :m ~ ! 2)J

~

~ "" 13 ~

10 12 a 16 1&

SwanllK>ightlcmj

Figure 1. Effect of Italian ryegrass sward height on average daily live-weight gain per lamb (ADG, glday) and live-weight production per hectare (LWG, kglha), (Silveira, 2002).

The reduction in LWG/ha on pasture height below 10 cm was due to restriction of , diet selection and low pasture intake. In contrast, on pastures taller than 15 cm, the

low performance per hectare was mainly due' to the stocking .rate reductio.n. The low

ADG on grass taller than 15 em can be explained by the low pasture quality. The

tallest treatment had high proportion of stem and dead material. Although the author

did not assess this, it is possible that daily intakes on the taller swards may have

been constrained because 'of a reduction in short-term intaRe rate resulting from the

low bulk density of herbage within the grazed horizons and an increased searching

component of grazing behavior as sward heterogeneity increased with maturiti

The poor performance of sheep in tall pastures may also be explained by the

endoparasitic infection. To verify this hypothesis different stra..ta of a ryegrass pasture

were cut.and submitted to different grazing methods (continuous and rotational) and

herbage allowances (10 and 20 kg dry matter (DM)/100 kg of LW). It was concluded

that high herbage allowance (with high pasture mass) favored animal infection with

Haemoncus contortus (Table 1). This increased infection was attributed to higher

moisture content within the pasture, and hence a better environment for the

development of infecti,ve larvae. In this case, the grazing method, with two days

grazing period and 20-32 days resting pe!iod, depending on the leaf live-duration (in

?rder to minimize the amount of senescent material), had no effect on animal

infection with Haemonchus contortus (P~goraro et al. 2008).

Table 1. Number of eggs per gram (EPG) collected from sheep under two different grazing managements and two pasture allowances.

Grazing method

Continuous stocking Rotational stockin

Fora e allowance 10% of live wei ht

1.032,64b 413,44b

(Pegoraro et al. 2008).

20%' of live wei ht 3.237,19a 3.023,94a

Similar to the work of Silveira (2002) with ryegrass, an experime~t was carried out in

the following year, with millet (Pennisetum americanum) - annual erect tropical

pasture - comparing lamb production from different pasture heights (10, 20, 30 and

40 cm) (Castro, 2002). It was found that millet should be maintained at around 30 cm

to maximize the lambs' weight gain (Figure 2).

140

~ 2 0

10G ~ .=. c ~ 80

6G

• 1>00 y:;; H,Wl· 6,~ 56 x - O,097"( ~ . 0,91

0. Glha y :a-281.S:S3 . 61 -,D13x - 10.(7~ A tJ.

r lI: 0.91 ' __ -:!.~~~

• /.: / "...,;+T I ,,~ ~~/ I I /~" • I I

/

II I I

. I I .~ I I 11 I I I . I I

,. 15 20 25

Sward height (em)

700 41 p 3 '

6(){} 'OJ

" '" ~

5()0 G ., ;;? (p

-<00 g,

~ 300 E:

I

200 ~ ~

100 " 40

Figure 2. Effect of milletsward height o~ average daily live-weight gain per lamb (ADG, Ida ~ and . Itve·welght productIOn per hectare (LWG, kglha), (Castro, 2002). 9 Y

The pasture managemen.t, allowing the grass be close to 40 cm ~eight, generated a

low gain per area due to low stocking rate:' Failure to increase, and the trend of

reduction of individual gain at high pastures can be explained by the research work

described by Carvalho et al. (2001). They showed, using Panicum maximum cv.

due to the time the animal requires to process (chew) the herbage consumed in a

bite.

.... c 'E

iii ::; . M

c: J. g '" ~ E

::! ~ 3 0 co a

" g

~ !!l g: f! co " '" " iil '" J!! ,

£

,. .. Sward height (em) Sward height (em)

Figure 3. Ingestive behavior (bite mass (- ), bite rate (0) and intake rate (A)) by lambs, grazing different pastures of Panicum maximum maintained at different heights (Carvalho et al., 2001).

Similar to erect tropical pasture, there is a Significant effect of sward structure of

prostrate grasses, such as Bermuda grass, on lamb performance. Carnevalli et al.

(2001) observed that sheep production with Bermuda grass reaches its maximum

when the pasture height is between 1S-20 cm. However, Piazzetta (2009),

comparing different production systems, suggested, that for weaned lambs, grazing

Bermuda grass (Cynodon spp cv. Tifton-8S): it is more important to provide a pasture

with high leaf density, rather than the height of the grass itself.

Natural Grassland In addition to the research projects conducted with cultivated pastures, investigations

were undertaken to examine the effect of sward height in native grasslands on the'

rate of intake by sheep and cattle. Gon<;:alvt;)s et al. (2009) conducting small-scale

trials on previously mown native swards, consisting predominantly of Paspalum

notatum and Axonupus a ffin is , showed that sheep grazing swards taller than 9 cm

reduced their intake rate. This reduction in intake rate was explained by the

reduction in bite mass due to the low pasture density. Several studies (Chacon and

Stobbs, 1976; Carvalho, 1997; Roman, et al. 2007) have shown that in addition to

intake being constrained by bite depth, even with prostrate species, the density of

the pasture is an important determinant of bite mass The low density of leaves in a

pasture, with a low leaf/stem ratio, can therefore reduce intake rate and thus limit

total daily intake. ,

... c- .,..

;:;- . ~

'" ::E .... ::B § • g Q

~

~ ~ -::J 0

=- E u ;; u <ii ' ~

.:. .s

.=: .. ' 0 .. .. • >000 .. '" .. .. .. ..

SWUd hdght (em) s;,. ~ 10

Figure 4. Bite mass (mg of dry matter OM . Sward h';gh, (an)

ewes (. ) and heifers (0) grazing n~tiv:::S~:r:~~a~~c b~C;: weight (MW)) and intake rate by ren eights (Carvalho et al., 2001)

Pasture Management Conclusion

Across a series of studies using various cultivated grass pastures it has been b d - species and natura

, 0 serve that similar relationships exist betw morphology and animal performance and out ut een swarc pasture management often h . P per hectare. Thus, changes ir

, ave greater Influence 0 . output than differences in for' n animal performance and

age species or the cultivar used Furth . .

observed that sheep are extremely responsive to changes in past~re ma~~::::~~ IS

Reviewing several stUdies with sh . eep, Carvalho (2004) established guid r f

grassland management relating pasture height and h b e lOes or nutritional requirement of different h . . er age mass to meet the

seep categories In a flock (Table 2).

Table 2._General references of sward height (SH ~ - -. - categories of gra . , c:; and herbage mass (HM kg OM/ha) for diffe;;

zmg seep (Carvalho, 2004) en Forages !Animal Category

Winter pastures Height (cm) HM (kg DM/ha)

Growing lambs 10-15 1600-2000

Dry ewes or in initial 213 pregnancy 10 1400-1600

Ewes in final 1/3 pregnancy and lactation 15-20 2000"2400 Summer pastures Growing lambs

prostrate 15-20 2500-3000

Species Dry ewes or in initial 2/3 pregnancy

10-15 2000-2500 E . wes In final 1/3 pregnancy and lactation

20-15 3000-3500 Summer pastures Growing lambs erect species

.' 25-30

Dry ewes or in initial 2/3 pregnancy 3500-4000

20-25 3000-3500 Ewes in final 1/3 pregnancy and lactation

30-35 4000-4500 I I

Having established the targets to be achieved in grassland ma~agement, the next

step is to determine how to achieve them. Presented below are the management

tools that can be used to achieve these goals.

TOOLS TO ACHIEVE GOALS OF PASTURE MANAGEMENT FOR SHEEP

Grazing Method The grazing method is a way to control pasture cover (sward mass) in order to fit the

requirements of grazing animals. Some stud ies have been made to compare

methods of pasture use. Appropriate grazing methods provide a m'eans of controlling

sward mass and height in order to allow grazing animals to maximize daily intake of

herbage dry matter. Various studies have compared alternative systems of grazing

methods, but have shown little difference between the different stocking strategies.

What is apparent is that, during periods of rapid pasture growth, a compromise

needs to be achieved between maximizing daily intake and animal performance, and

maximizing the efficiency of utilization of the green herbage grown and reducing loss

of senescent material .

During periods of rapid pasture growth under rotational" stocking management, a

compromise between maximum animal ~erformance and minimal pasture

senescence will crucially depend upon pasture allowance (kg herbage OM per kg

animal live weight), rather than the precise cycle of rotation . During periods of rapid

pasture growth under continuous stocking management, grazing pressure will have

to be increased by increasing stocking density in order to maintain a suitable pasture

height and avoid the devel0pment of senescent patches within the sward and

avoidance by the animals. .

A research project was recently initiated to examine the effect of grazing method

during the autumn-winter period on ingestive behavior and performance by ewes and

lambs, and on sward structure in a natural pasture. Rotational and continuous

stocking managements were compared, at high and low herbage 'allowances, during

the initial two thirds of pregnancy when ewes' food requirements are low. During the

final third of pregnancy ewes were provided a high forage allowance under

continuous stocking management. The results of this work are s.till being evaluated.

One of the study hypothesis is that over several years, rotational stocking

management with a low herbage allowance during the autumn-winter period, may 2

favor the development f ' P 0 prostrate and higher-digestibility species, such as

aspalum notatum. Changes in forage allowances were observed in the Rio Grande

do Sui as being beneficial to cattle between spring d . h b ' . an summer penod. High

er age allowance In spring promoted better animal performance in th . (Soares et aI. , 2006). e summer

P~eliminary analyses of the data show that, in natural pasture during the autumn-

winter penod, grazing method had a important effect . . Com . on Ingestive behavior

panng average behavior over 7 days on a rotational stocked paddock with tha;

on. a continuously stocked paddock, showed that under continuous stockin the animals grazed significantly (P=O 016) 'b ' g . " . onger, ut rum inated and remained idle for

Significantly (P=0.051 and P=0.058) less time.

This increased grazing time was reflected !n J animals. I . a greater distance traveled by the

n continuous stocking manag t th . . emen , e ewes traveled on average 65%

more distance than the rotational stocking management (Figure 5) Th f allowance h d . . e orage

a no Important effect on traveled distance. The animals seem to

compensate for the lack of diet selection oppo'rtunity by reduc' d' . Ing energy

expen Iture, as there ~as no significant difference between the grazing methods and

forage allowance on ewe weight change in this period. \

The fact the h~rbage allowance 0: native sward has little effect on ingestive behavior attracts attention Very few st d' .

. '. u les, With un-supplemented animals, are conducted dunng the autumn-winter period. In winter, the pasture is affected by cold and . frosts, lowering the gre I f II severe th . en ea s a owance, and consequently tHe nutrition'al quality of

e . pasture. I.n thiS scenario, the forage allowance becomes less important. The

obVIOUS questlo? IS: What pasture management should be used in this period of the year? Can the grazing method help?

Figure 5. Sheep displacement on natural pasture under different grazmg methods and herbage allowance A: Rotational 18% forage allowance; B: Rotational 12% forpge allowance' C. Continuous 18% forag~ allowance; 0 : Continuous 12% forage allowance; Red Line: Limit of paddocks; Green line: Sheep displacement.

- Supplementation Supplementation is an altemative management by wh ich the herbage available' for

grazing can be increased in relation to animal requirements. Although concentrate

supplements be an expensive resource, compared with pasture herbage, it is a safe

investment because it does not depend on climatic variables. It can be an

important tool , especially when used strategically for growing an imals or in situations

requiring an immediate response (Ganzabal, 1997). The great challenge for

supplementation, however, is the variability of an imal response and the difficulty of

pred icting it precisely. Because little is known about the effects of supplements on

the ingestive behavior by sheep in the present context, especially when ,grazing

complex swards, it is difficult to pred ict the outcome with confidence. In light of these

challenges, a study was conducted (David, 2009) to determine the minimum level of

metabolisable energy (ME) and rumen degradable protein (RDP) that would still

allow maximum 'weight gain of ewe-Iambs (hoggets, -8mths of age) grazing natural

pastures over the winter period in southern Brazi l. For this ewe lambs were supplied

with conce,ntrate to levels of 0, 33,66 and 99% of ME and RDP requirements .

!;lased on nutritional assessment of hand-plucked , pasture samples, the result

showed that the limitations of large native pastures during the winter are the high

fiber content and' the chemical composition-of the cell walls, which are responsible

for the low levels of digestible organic matter (46, 9%). For the 13,8% of crude

protein present in the forage , 45% were linked to the fiber, of which 18% completely

unavailable.

Linear regression analysis of the data showed a sign ificant effect of supplementation

on average daily weight gain (ADG=0.0198 +0.0015x; R2=O,96) and on weight gain

per hectare per day GHAD=0.139+0.015x; R2=0.96). A significant linear response

was also found with increasing' levels of a_balanced supplement on pastur.es of

Cynodon spp cv. Tifton-85 and ryegrass (Lolium multiflorum) at high herbage

allowances (Monteiro et aI. , 2009).

~ -. ., ~ c-:::: ;::; B

l ,800 1,600

1,400

1.200 1,000

0,800

0,600 0,400

0,200

0,000

0

y - 0,139 + 0,0 1526" cv- J 2,82; R2 - 0,96; P<{),OOO J

33 66

Supplementation Levels % of ME.RDP supply

99

Figure 6. Effect of supplementation ~evels providing 0, 33, 66 or 99% of total metabolizable ene~ (ME) and rumen degradable protem (RDP) requirement on live weight gain per hectare per diigy

(GHAD) (David, 2009) y

The stUdy also aimed to identify possible predi~tors of the maximum potential live­

weight gain response to the supplement. Regression analysis of ADG for un­

supplemented vs supplemented animals with in each block showed th at the potential

response to supplementation was dependent on the rate and amount of weight lost

over the winter period (Fig. 7). These results suggest that the energy deficit

experienced by an animal is an appropriate predictor of potential response to

supplementation. Finally, it also demonstrates the possibility of expressing

supplementation as a percentage of the nutritional requirements, which would allow

comparison of different studies on the same basis.

" 6,0025 ,

~~ ~ 0,0015 ~ 0.001 J , I

0.0005 ~ . i e i

• y = -OPIl!'h:-;.o.ooI7

i =0,0135'

i • -0,000-; +I_~~~_~_-,-_-,-_--,-_--,-_~ __

-O,05e -&P30 -0,010 OPI0 0,03& Op5~ O,PiO 0,090 0,110 0,139 -

AOO(k;) No JUp'pl'!~nt"~d

Figure 7, Relation between ~~erage 1aily gain without supplementation and the degree of slope of e supp emented animals (DaVid, 2009).

___ ----~_:_-_::_=_=_=_=.=_::- . bles affected by pasture SUULIU'C, ~UV" . behavior observations, varia

~ In the ingestive d of feeding stations, were not of displacement rate an u~e

as biting rate , measures t r This demonstrates the b th levels of supplemen a Ion.

;: (P> 0.05) influenced yet On the other hand, grazing on different treatmen s.

uniformity of pasture allowance t t as given to the animals. The . I (P <0 01) as more concen ra e w

time decreased ilnear y . d ariations (P <0.05) related d the number of meals showe v

duration of the meals an . . trol by parameters of rumen I f the diet and possible con

to the nutritional leve 0 - . ., hen different levels of . est that In situations w

fermentation . The results _sugg 'IS a change in how the animal t d to animals there

concentrate are supplemen e

explores the pasture-

Nitrogen Fertilization . is another tool that has an important. influence on the The nitrogen fertilization .' heep production is clear In the

The effect of nitrogen In s performance of sheep.. . . d lambs grazing an annual

- . (2003) who worked With ewe an research work of Freitas , . , ' levels has a greater effect

. (2003) increaSing nitrogen -ryegrass. According to Freitas . ' f ' d' 'd al animals. As shown in Figure . on stocking rate than on the performance 0 In IVI U

5 the AOG of lambs is not affected by different nitrogen levelS.

, . d ositivel{with additional nitrogen. The lowest The LWG/ha increased linearly an p --1 d 220 kg LW/ha whereas the

/ ' f't en (25 kg ha ) produce annual application rate 0 nI rog 1 d d more than 500 kg LW/ha. highest annual application rate (325 kg ha- ) pro uce

Q ,9GO

0 , 8 00

~ . TO "

]\ >l ,U O

0 ,5>: 0

] \ D ,4CO

$ O , lO'3

tl Q ~ ,: Qil

-< >l . ' CO

0 ,0100

y . 1 , 0010,1 t 19,~ 9

It ' - 0 ,6 6 4

T - 6 f ...o!1. + 'l ,lll l

~J .. 0 .07l 1l

.. ......... ; _' - -' - - -f- .. - - ' - -,-.: .:,:,::, .:,:: :. ~ !tJ . O. H :..,. _-

Levels of N fertilization (kglha) -;;, - -

'" '" Levels of N fertilization (kgIha)

'"

a • and average daily gain (AOG) by ewes (x) and Figure 8. Live weight gain per hect~r~.fL~G::t~ Jiff~rent nitrogen levels (Freitas, 2003)

lambs (+) on ryegrass Ie liZ

kg of nitrogen applied to pasture. This re lationsh ip is essential to demonstrate the

economic va lue of soil ferti lization.

Early Weaning Early weaning is a management tool that can be ' used when there is a lack of forage .

After the lambs are weaned , the dry ewes can be placed on a pasture of poor

quality. With early weaning it is crucial to place the lambs on pasture with low

contamination of worms and with leaves easily grazed by the animals. Poli et al.

(2008) and Ribeiro et al. (2009b and 2009c), comparing different lamb production

systems, showed that early weaned lambs (around 45 and 60 months of age) requ ire

food of good quality, readily available and free of gastrointestinal parasites. In this

case, feeding a foncentrate diet, or leasing of areas outside the property may also

be interesting alternatives. Early weaning will be more fully discussed in the section

on sh-eep feeding systems.

SHEEP FEEDING SYSTEMS

Given the progress of studies on sheep pasture management, research focusing on

the development of lamb production systems on pastures began in 2003 at the

ResearcQ and Production of Sheep and Goats Center (www.lapoc.ufpr.br) in Federal

University of Parana. From information and results of the management of cultivated

pastures established for lambs in the South (Silveira, 2002) and Southeast

(Carnevalli et aI. , 2001) of Brazil , experiments were conducted to assess different

feed production systems for lamb meat production ,. between ,2003 and 2005 in

LAPOC. In the first years four different systems were compared: (1) early weaned

lambs (between 45 and 60 days old) and finished exclusively on pasture, (2) un·

weaned lambs (suckling lambs) and finished exclusively on pasture, (3) suckling /

lambs on pasture and supplemented with concentrate at 1 % of L W /day ina creep

feeding'. These systems were compared among themselves , and also with an early

weaning system in which lamb~ were confined in feedlot and offered a high energy

density diet (ME = 2.5 Mcal/kg OM/day) ad libitum. It was assumed that the best

performance and carcass traits (weight, iricome and degree of finish ) would be

obtained from feedlot system. The study was carried out on tropical pasture

Cynodon spp cv. Tifton·85 (2Q03/2004) and temperate pasture annual ryegrass

rf e ana pruuu,.,Llv"y . 4/2005). The results for pe ormanc .

~ (Lolium multlflorum) (200 . I (2008) and during the winter during the summer have been published by Poll et .a. .

. . t I (2009b and 2009c) and are summarized In Table 3. ~ by Ribeiro ea . .

. ance in lambs production systems, with 32-34 kglLW In

Table 3. Productivity and ammal perform ltd in LAPOC between 2003 e 2005 Summer and winter pastures eva ua e -

Pasture Variables _

ADG (glanimal/day)

Tifton-85 Slaughter age (days)

Productivity (kg of LW/ha/day)

ADG (g/animal/day)'

. Systems

Weaning

+ Pasture

107 c

1131

4,21

115 c

160

3,46

Without

weaning +

Pasture

281 b

101

3,37

303 b

106

2,19

Creep

feeding +

' Pasture

282 b

105

3;(34

294 b

106

2,52

Weaning +

Confinament

437 a

94

338 a

96

Ryegrass Slaughter age (days)

Productivity (kg of LW/ha/day) . . <0.05). Source: adaptation of Po/i et al. (2008) -

the feedlot lambs (95 days), in both studies.

The study showed that it is important to keep the lamb with the ewe in order to obtair

good performance on pasture. The importance of the ewe on production system can

be seen by a marked difference in the individual performance of lambs betweer

systems with and without weaning on pasture. Early weaning reduced , on average

60% of the lamb ADG. Moreover, there was a mortality rate of 20% for weaned

lambs finished on ryegrass as a resu lt of intense worm infection.

The ewe presence not only improves the nutritional status of the lamb through the

milk, but also plays an important role in animal health and stress conditions. The

break of maternal bond, the limited experience of grazing and the lack of ability to

take advantage of the forage consumed by the young ruminant characterize

potentially stressful factors, which are exacerbated by early weaning. Assessing the

influence of early-weaning under sanitary conditions and stress imposed on lambs

finished on pasture, Fernandes (2010) observed that early weaning led- animals to

chronic stress, resu lting in immunosuppression and increased susceptibility to worrr

infection. It was concluded, therefore, that the maintenance of the ewe-Iamb bond is

impo'1ant for minimizing stress conditions and improvi~g the health of grazing

lambs.

Despite the differences in ADG of lambs, the total animal production was similar (P>

0.05) between grazing systems within the summer and winter periods(Table 3). The

low ADG of weaned lambs and finished on pasture was offset by the greater

stocking rate. In both systems where the lambs remained with t~eir ewes stockin£

rates averaged 12 lambs/ha in summer and 8 lambs/ha in winter, whereas in the

weaned system stocking rate averaged 18 lambs/ha in summer and 31 lambs/ha in

winter. Thus, while productivity was partly offset by differences in stocking rates,

early weaning was not an efficient means of increase stocking rate because weaned

lambs were 60 days older at slaughter and showed a high mortality rate caused by

worm infection. -

Following the research studies to asses$ lamb production systems, in 2007 a

research project was carried out to compare different forms of supplementation for

un-weaned lambs at pasture. The following systems were assessed: (1) lambs kept

- exclusively on pasture, (2) lambs kept on pasture and sUpplemented with a

concentrate of 2% LW/day using creep gates, (3) lambs kept on pasture and with a

free access to legume pasture using creep gates. The experiment was set up on a

bermudagrass (Cynodon spp. Cv. Tifton-85) sward overseeded with annual ryegrass

(Lolium multiflorum). The legume used in the creep grazing was white clover

(Trifolium repens).

The treatments providing o/eep feeding and creep grazing showed siroilar lamb

performance (P> 0.05) and allowed the lambs to be slaughtered younger than u~­

supplemented lambs (Table 4). Thus, lambs offered white clover ad libitum by creep

grazing can achieve a similar level of live weight performance as lambs offered

concentrate at 2% LW/day through creep feeding. Although the ADG of

supplemented lambs were higher than those of the un-supplemented lambs, the

productivity per hectare was not affected (P> 0.05) by supplementation. The lack of

response to the availability of creep feeding and creep grazing on pasture production

resulted in similar levels of lamb production. It is important to note that the lambs

that had access to creep grazing, and creep feeding showed low outputs of gastro­

intestinal worm eggs (Ferreira, 2009; Figure 6).

Table 4. Lamb performance and production per hectare at a slaughter weight of 32-34 kg LW, when offered mixed grass pastures, either without a supplementary feed source, or with access via a

creep gate to a concentrate diet or a white clover sward, evaluated at LAPOC in 2007 . •

Systems

Pasture Variables Creep Creep Only pasture

feeding grazing

ADG (g/animaVday) 204 b - 308 a 274 a

Ryegrass Slaughter age (days) 95 81t 89

+ Tifton-85

Productivity {~g of LW/ha/day) 1,8 2,4 2,4

Lowercase letters in the same line differ by Tukey test (P<0.05). Source: adaptation from Ribeiro et al. (2008) and Silva et al. (2008) .

.

/

8000

(.:> 6000 "-O;l

4000

2000

0

"

2 3

Evaluation 4

Figure 9. Gastro-intestinal worm egg output per gram

offaeces (EPG) from lambs on three alternative grazing

treatments: not

• <> • Not supplemented -+- Creep Feeding - C . ~ reep Grallng

Supplemented; offered concentrate Supplements (creep feeding); offered access to a white clover sward (creep grazing) .

Ingestive behavior by grazing lambs was . assessed In diff t f .

and Without, creep feeding d . eren eedlng systems: with an creep grazing. Three diurnal (fro

assessments were performed (Figure 10). m dawn to dusk)

Lambs not supplemented ........ ;~;;;:=C;===:J====:J

Lambs in creep feeding

Lambs in creep gazing

60% 80% 100%

Percentage of day

Figure 10. Proportion of the day spent on di;erent activities b . offered creep feeding or o"ered Y lambs ellher not supplemented

, "'" creep grazmg. '

Grazing time differed (P <0 05) b tw . . e een different lamb feedin

highest for unsupplemented lambs (395 .) g systems, being min and lowest for lamb I

using creep feeding (274 min) Th' . s supp emented . IS occurred because the unsu I

extended their grazing activity (54%) t . . pp emented lambs o 0 meet their nutritional .

concentrate offered at 2% LW/d . r~qUlrements. The o ay In the creep feeding t t

substitution of intake of the p t rea ment may led to a as ure, resulting in decre . d .

lambs. Grazing time on th . ., ase grazing time (27%) by the e creep grazing system wa . t .

grazing of white clover account d f . S In ermedlate - (348 min). The e or approximately 50% of the total tim f .

eo grazing.

. '. not affected by the treatments (P> 0.05), tel h 'dling Once. the rUminating time was . . (R = -0 82), indicating that ime was inversely proportional (P <0.05) to feeding time . . . . .

:he ""'''';0" ;" feed;", I;me w" atthbuled 10 Ihe ;""ea,e '" ,d"", I,me. ,

~ . not affected (P> 0.05) by creep feeding and cree~ . Time spent sucking was also . . f 1 58 min. In fact, to assess

. h ed an average sucking time 0 . grazing . The animals s ow . th me-tabolic profile of lambs fed

t te supplementation on e the influence of concen ra t t' n determines the increase

Fernandes (2010) found that supplemen a 10 . . f on pasture, - h' h reflects better nutntlonal status 0 of serum albumin and glucose, w IC

supplemented lambs.

ffect of the feeding h racteristics produced as an e In relation to the carcass ca. f d that un-weaned lambs,

2003 and 2005, It was oun . systems assessed between . dl t I bs had similar amounts of fat

d t and the fee 0 am whether supplemente or no , th eaned lambs submitted to a

deposited in the loin (P> 0.05,) (Table 5) .. However'(pe ~ 05) than un-weaned lambs

nts of fat In the leg <. feedlot showed greater amou . . (P 0 05) to lambs from the creep

t but they were Similar >- . kept exclusively on pas ure, 'th asture showed the lowest feeding treatments . The weaned lambs fed only WI ,p . /

unt of fat deposited in the loin and leg (P <0.05).

amo • hter and characteristics related to carcass Table 5. Cold carcass yield, body con~~o: s{~e :~:~a%~shed on wintw pasture systems evaluated fat content of lambs s/au,;!htered at !;-LAP6c f,pm 2004 to 2005 .

Variables

Cold carcass yield (%)

Subcutaneous fat- Loin(g )

Weaning +

Pasture

40,0 b

28,7 b

SystefT1s

Without weaning +

Pasture

45,3 a

79,4 a

Creep feeding +

Pasture

47,2 a

85,5 a

W,eaning +

Confinement

45,0 a

96,6 a

( ) 55,0 c Subcutaneous fat- Leg g . . t I (200gb)

. .. iffer b • Tukey test (P<0. 05). Source: adapted from Ribeiro e a.

121 ,7 b 160,0 a 152,2 a

Lowercase letters m the Ime d y and Fernandes (2008).

\ . roduction and quality of carcasses. Greater fat The fat content affects directly the p . . Id and carcass quality is

" . . d with a higher carc.ass Yle , deposition IS associate , . k t According to Pereira Neto

t t as required by the mar e . determined by t~e fat con en , . h the body condition score

' I u htered when It reac es (2004), lamb should be sag. t the reqU irements of the !3razilian,

3 0 and 35 (in a 5-polnt scale) to mee between . .

market. This condition was observed -in the un-weaned lambs and in the feedlot

lambs (Table 5). Similar carcass characteristics were also observed in the feed

systems assessed in 2007, where Supplemented lambs offered supplements at 2%

LW/day using creep feeding or with white clover using creep grazing , did not alter the fat content or carcass yield.

From the results of studies on sheep feeding systems carried out between 2003 and

2005, an economic analysis was performed (Barros, 2008). Highest returns were

obtained in systems where the lambs were nof weaned and kept on pasture.

Weaned lambs finished ih a feedlot, espeCially when fed with alfalfa hay and

concentrate (2003), and weaned lambs finished on pasture (2004) resulted in

economic loss. The most important items for sheep production costs were: labor . ,

(31%), foo~ (24%), conseryation of buildings and facilities , machinery and equ ipment

(11 %) animal health (10%), technical aSSistance (8%), and taxes and fees (4%),

among other minor costs. This emphasizes the importance of efficient use of labor In enterprises, a component possibly not considered in most Brazilian farms.

CONCLUSION

Studies in Southern B!'azi! have shown that it is feasible to produce lamb meat from

pasture. However, it is essential to have a clear target in relation to adequate pasture

management and to adjust the production system accordingly. It is also important to

consider that sheep are very responsive animals in relation to quantity and quality of

food, and that the ewes have an important role during the growth Of the lambs at pasture.

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