Livestock Research for Rural Development 18 (11) 2006 Guidelines to authors LRRD News

Citation of this paper

Effect of strategically supplemented pregnancy allowance on nutrient utilization and reproductive performance of goats

A Rastogi, N Dutta and K Sharma

Centre for Advanced Studies in Animal Nutrition, Indian Veterinary Research Institute, Izatnagar-243 122, India
directorcasan@ivri.up.nic.in


Abstract

Gravid does (18) were randomly divided in to 3 groups, provided wheat straw ad libitum and supplemented with concentrate mixture at the rate of 20g/kgW0.75 throughout the period of study. Additional 20g concentrate mixture/kgW0.75 as pregnancy allowance was given to gravid does from 61 days post-mating to term, 61-90 days post-mating and 121 days post-mating to term to HH (High-high), HL (high-low) and LH (low-high) group, respectively.

Mean daily dry-matter intake (g/kg W0.75) increased linearly during first three months of gestation after which it became stable. Daily dry-matter intake of goats during metabolism trial (after 135 days post-mating) was significantly (p <0.01) lower in treatment HL as compared to similar intake in HH and LH treatments. Digestibility coefficient of dry-matter was significantly (p <0.01) lower in treatment HL in comparison to comparable values between HH and LH treatments, whereas crude protein digestibility was significantly (p <0.01) higher for treatment LH followed by treatment HH and HL, respectively. Live weight changes, foetal growth and reproductive performance of goats on treatment HH and LH were statistically similar and significantly (p <0.01) better relative to does on HL.

The study indicates that last month of gestation is the period of most rapid foetal growth necessitating supplementation of pregnancy allowance to economize production and minimize reproductive wastage in goats.

Key Words: Foetal growth, gravid does, pregnancy allowance, reproductive performance, strategic supplementation


Introduction

Goat keeping has assumed a key position in the rural development programmes in the developing countries. They contribute meat, milk, fiber, manure and functions that are significant to the productivity, stability and sustainability of many farming systems in third world countries where interdependence of crops and livestock is well recognized. Majority of the world's goat population is found in the small holder farming system where nutritional conditions are often sub-optimal (Sibanda et al 1999). With the development of goat rearing as an industry, upcoming trend is to keep goats under stall-fed conditions, which require even more attention for supplying the nutrients. Under these intensive management conditions, reproduction is one crucial aspect from nutrient requirements point of view. Reproduction increases the animal's requirement for nutrients, but conversely, the nutrient supply to animals can influence their reproductive processes. Moreover nutrient requirement for reproduction varies considerably from one phase of reproductive cycle to another.

Dynamics of caprine foetal growth indicated that the rate of weight gain was maximal at 120 days (d) of gestation (Osuagwuh and Aire 1990). Though literature is scanty on the effects of supplementary feeding of pregnant goats based on intra-uterine growth pattern, it has been observed that nutrient diversion to foetus and other associated tissues is extremely small before sixty days of gestation. In mid pregnancy, the nutrient requirements of foetus are still low, but placenta must grow at this time and if growth of placental tissue is restricted by low plane of nutrition, it will be unable to adequately nourish the foetus in final stage of pregnancy and consequently birth weight will be reduced (Osuagwuh et al 1980). Rapid rate of foetal growth during the final six weeks of pregnancy imposes a metabolic challenge to the doe, which is met by the mobilization of maternal body tissue (Osuagwuh and Aire 1990) and this may result in weight loss of doe, if the dietary supply of nutrients is inadequate (Sibanda et al 1997). However, it has been suggested that retardation of foetal growth late in gestation should have a less severe effect on subsequent neonatal development than retardation at an early stage as bovine foetal growth is attributed more to hypertrophy than to hyperplasia with an increase in foetal age (Prior and Laster 1979). An unscientific approach to animal feeding during pregnancy may lead to reproductive wastage resulting from either abortion or neonatal death due to low birth weight resulting from malnutrition of pregnant does (Osuagwuh and Akpokdje 1981; 1986) or dystocia due to absolute foetal oversize as a result of high level of feeding throughout gestation (Osuagwuh et al 1980). Keeping this background in view, the present work aimed to investigate the effect of strategically supplemented pregnancy allowance on the nutrient utilization and reproductive performance of stall-fed goats.


Materials and methods

Experimental animal

Twenty-one local non-descriptive adult does of about 3 years age, with a mean initial live weight of 16.26±0.82 kg were taken as the experimental animals. Local goats of the area are unimproved indigenous medium-sized animals with variable coat colours and are kept primarily for meat. Animals were teased twice daily for oestrus detection and were bred by a single buck during standing oestrus. Does returning to heat again in the subsequent cycle were re-bred. Eighteen confirmed pregnant goats (confirmation by ultrasound technique at 60 days post mating) were randomly allotted to three dietary treatments HH (High-high), HL (High-low) and LH (Low-high) with each treatment consisting of 6 does in a completely randomized block design. All the does were penned individually in ventilated sheds and allowed exercise out-door adjacent dry paddock daily between 08.30 to 09.30h.

Experimental procedures

All does were offered a basal diet of wheat straw ad libitum throughout the experiment supplemented with concentrate mixture (Table 1) at the rate of 20g/kgW0.75 during early gestation period (up to 60 days post mating (DPM)). Additional supplementation of 20g concentrate mixture/kgW0.75 as pregnancy allowance was given from 61 DPM to term, 61-90 DPM and 121 DPM to term to HH, HL and LH group, respectively. 250g of vitamin mixture was added to each batch of 100 kg concentrate mixture to take care of daily vitamin A requirement of animals.


Table 1.   Ingredients and chemical composition of feeds (% DM)

Attributes

Concentrate Mixture

Wheat Straw

Ingredients, %

Wheat bran

55

-

Maize

20

-

Soybean meal

22

-

Mineral mixture

2

-

Common salt

1

-

Chemical composition, %

OM

92.3 0.5

93.4 0.2

CP

22.9 1.5

3.1 0.1

EE

2.3 0.1

1.4 0.3

Total Ash

7.7 0.5

6.6 0.2

CF

9.1 0.3

39.7 0.4

NDF

32.10.3

83.8 1.1

ADF

10.90.4

57.5 0.4


Daily allowance of the concentrate was offered in single meals in the morning; wheat straw was then offered for ad libitum intake after ensuring that the goats had consumed the concentrate. A metabolism trial of 7days was conducted after 135 DPM during which the gravid does were housed in individual metabolism cages. Samples of feed offered and refused were collected daily and oven dried at 80 ± 2°C for dry-matter (DM) estimation. Dried samples were pooled, ground and stored for further analysis. Similarly, total daily (24 h) faecal output was recorded and a sub-sample (20%) collected and dried in hot air oven to a constant weight for DM estimation. Representative samples of daily faecal and urine collection of each animal were pooled for 7 d and preserved in 1:4 sulphuric acid (v/v) for N estimation. Other sub-samples were retained for further chemical analysis.

Live weight changes and pregnancy variables

All the does were weighed, before feeding and watering, immediately after buck's introduction and then at fortnightly intervals to find out the BW changes during the study from mating to 24 hours post-kidding. BW of both does and kids were recorded within 24 hours of kidding. The does were weighed after expulsion of placenta. Pregnancy variables (products of pregnancy, foetal growth rate and average daily weight gain of does) were derived from the live weight changes of gravid does based on the assumptions that BW of gravid does during gestation indicate foetal prenatal development and secondly, pregnant goats grew at a constant rate during gestation (Amoah et al 1996; Akingbade et al 2001).

Chemical and statistical analysis

Representative sub-samples of the feeds offered and refused and faeces were analyzed for proximate composition AOAC (1995) and fibre fractions (Van Soest et al 1991). Urine samples were analyzed for N (AOAC 1995). Results obtained were subjected to analysis of variance, and treatment means were ranked using Duncan's multiple range test (Duncan 1955). Body weight of pregnant does at mating and pregnancy variables were subjected to regression analysis by programming and processing in a personal computer.


Results and discussion

Intake and nutrient utilization

Chemical composition of the concentrate supplement and wheat straw used in this experiment are given in Table 1. Mean daily straw intake, concentrate intake and DMI (g/kgW0.75) of gravid does during different phases of gestation is depicted in Figures 1a,b,c.



Figure 1a. 
Average daily concentrate intake (g/kgW0.75)
during gestation
 


Figure 1b.
 Average daily wheat straw intake (g/kgW0.75)
during gestation
 


Figure 1c.
 Average daily DMI (g/kgW0.75)
during gestation


Irrespective of the stage of pregnancy or treatment, straw intake (g/kgW0.75) of gravid does decreased with the increased dietary level of concentrate. The mean total DMI (g/kgW0.75) of does was similar (P<0.05) irrespective of dietary treatments. Mean wheat straw intake of does on treatment HL and LH was significantly (P<0.05) higher than their counterparts on HH treatment.

The daily intake of DM and OM (g/d or g/kg W0.75) during digestion cum metabolism trial was significantly (P< 0.01) lower for treatment HL in comparison to comparable intake on treatment HH and LH (Table 2).


Table 2.   Effect of strategic feed supplementation during digestion cum metabolism trial on nutrient intake and utilization

Attributes

Treatments

SEM

P Value

HH

HL

LH

Intake, g/d

 

DM

559b

383a

553b

23.1

0.021

Concentrate

396b

180a

395b

25.6

0.025

Wheat straw

163a

303b

158a

11.2

0.038

Intake, g/ kg Wo.75 /d

 

 

 

 

 

DM

54.3b

40.9a

54.3b

2.0

0.020

OM

50.3b

40.4a

50.2b

1.8

0.028

Concentrate

38.5b

19.3a

38.8b

2.4

0.041

Wheat straw

15.9a

21.7b

15.5a

1.3

0.050

Nutrient digestibility, %

 

 DM

66.5b

57.6a

67.3 b

1.3

0.049

 OM

69.8 b

61.6 a

70.7 b

1.3

0.047

 CP

71.5 b

58.2 a

78.9 c

2.2

0.050

 EE

70.5

65.7

73.8

2.1

0.309

 NDF

55.2

52.7

54.6

1.2

0.087

 ADF

51.5

51.9

48.5

0.9

0.089

Nitrogen balance, g /d

 

 

 

 

 

Intake

15.6 b

7.1 a

15.9 b

1.1

0.036

Balance

7.9 b

1.3 a

9.1 b

0.9

0.029

N-retention,% of intake

50.9 b

15.8 a

56.8 b

4.9

0.030

abc Means with different superscripts in a  row  differ (p< 0.05).

   Treatments HH, HL and LH signify strategic feed supplementation (@ 40g /kg W0.75) during gestation from days 61 to term, 91 to 120 and 121 to term, respectively


The intake of concentrate moiety comprised proportionately about 0.71, 0.47 and 0.72 by gravid does in treatment HH, HL and LH, respectively, during the trial. Intake of wheat straw moiety was proportionally higher (P<0.05) in treatment HL (0.53) relative to HH (0.29) and LH (0.28). Digestibility coefficient of DM and OM were significantly (P<0.01) lower in treatment HL as compared to similar values for HH and LH treatments. However, digestibility of fiber fractions was comparable among gravid does irrespective of level of supplementation. Interestingly, crude protein digestibility in gravid does was significantly (P<0.01) higher for treatment LH followed by treatment HH and HL. It is well known that a decrease in roughage to concentrate ratio increases the dry matter intake due to reduction in cell-wall contents and related bulk density of concentrate mixture (Waldo and Jorgason 1981; Kawas et al 1991). However, the increased proportion of dietary concentrate with high level of soluble carbohydrates (as observed in goats on HH and HL treatments) do not stimulate fiber digestion in the rumen because it supports the growth of starch-digesting microbes at the expense of cellulolytic microorganisms (El Shazly et al 1961; Kawas 1984). Improved CP utilization and nitrogen retention in LH may be attributed to possible increase in efficiency of utilization of consumed nutrients, particularly proteins as a result of realimentation to a higher plane of nutrition (Baker 1982). However, the net N balance (g/d) was lowest (P<0.01) in treatment HL due to lower intake.

Live weight changes, foetal growth rate and reproductive performance

The experimental does had similar (P<0.01) body weight at mating, 21 weeks of gestation and 24 h post-kidding irrespective of treatments. Derived pregnancy variables like pregnant does average daily gain (PGADG, g/d), products of pregnancy at 21 weeks of gestation (kg) and foetal growth rate (g/d) were significantly (p<0.01) lower in treatment HL than the comparable values obtained for HH and LH treatments (Table 3), as was the cumulative foetal growth (Figure 2).



Figure 2.
   Effect of strategic feed supplementation on cumulative foetal growth in gravid does
 



Table 3.  Effect of strategic feed supplementation during gestation on live weight change and reproductive performance of does

Attributes

Treatments

SEM

P Value

HH

HL

LH

Body weight  of does, kg

 

At mating

16.1

15.9

16.8

0.8

0.121

21 weeks of gestation

23.3

19.9

23.0

1.0

0.201

24 hours post kidding

19.0

17.2

18.3

0.9

0.325

Gross gain  at 21 weeks  gestation

7.2b

4.0a

6.1b

0.5

0.031

Reproductive performance of does

 

Net Gain

2.9b

1.3a

1.5a

0.31

0.050

No. of live kids at birth

6

5*

6

-

-

No. of still birth

0

4**

0

-

-

Does mortality, %

0

33.3

0

-

-

Gestation Length, days

149

149

152

0.4

0.411

Kids survivability after 1 week, %

100

40

100

-

0.049

Kids birth weight, kg

2.1 b

1.7 a

2.3 b

0.1

0.025

Pregnancy Variables

 

PGADG, g day -1

47.8b

26.8a

40.9b

3.0

0.025

Products of pregnancy at 21 weeks of gestation

4.1b

2.7a

4.7b

0.3

0.028

Foetal growth rate, g day -1

28.6b

18.2a

31.0b

1.8

0.035

 abc Values with different superscripts in a row differ significantly  (P<0.05)

 * One goat was carrying twins.

 ** Two goats, carrying twins, died during parturition

      Treatments HH, HL and LH signify strategic feed supplementation (@ 40g /kg W0.75)    during gestation from days 61 to term, 91 to 120 and 121 to term,  respectively


The gross gain in weight at 21 weeks of gestation was significantly (P<0.01) lower in treatment HL relative to comparable gross gain observed in HH and LH groups. However, net gain (kg) of gravid does was significantly higher in treatment HH than the values obtained for does under HL and LH treatments. Usual changes in the live weight of dam during gestation are often assumed to be indicative of pre-natal development of foetus (es) (Amoah et al 1996). Therefore, changes in the weight of gravid does can be used to monitor foetal development (Akingbade et al 2001). It has been reported that during late pregnancy there is preferential nutrient utilization for foetal growth at the cost of mobilization of maternal body tissues (Osuagwuh and Aire 1990), which results in weight loss of doe if the dietary supply of nutrients is inadequate (Dayeh et al 1996; Sibanda et al 1997; Al-Totanji and Lubbadeh 2000). The pattern of foetal growth rate in does during the experiment corroborate these observations and also indicate that last month of gestation is the period of most rapid foetal growth.

Mellor and Matheson (1979) has reported that abruptly imposed severe under-nutrition, around 120 d of gestation could slow down, or in some cases halve foetal growth within 3 d. Therefore, nutritional stress imposed during this period on the gravid does of treatment HL resulted in poor foetal growth and also loss of body condition of the pregnant animals, especially those bearing the twins. It may precisely be the reason of mortality of two twins carrying does during parturition, in treatment HL. They showed low glucose level (34.5 mg/dl) at 135 DPM and were in the state of posterior paresis resulting in prostration during last week of gestation, with gradually reduced straw intake. These does appeared to be in distress at the time of labor with poor uterine motility. One doe died after delivering one kid (1.38 kg BW) and another kid was removed from the uterus during post-mortem and was found poorly developed (0.9 kg BW). Other doe died immediately after showing the signs of imminent parturition. Post-mortem of these does revealed very poor body condition with little body fat reserves. In contrast, foetal growth pattern of LH treatment clearly indicates that foetal development was improved after supplementation of pregnancy allowance (120 days post mating to term) with does giving birth to kids with normal birth weight and 100% survivability upto one week of age. This was contrary to the reports indicating the gestation period from 90-120 d to be most sensitive to nutritional stress in West African Dwarf goats (Osuagwuh and Akpokdje 1986; Osuagwuh and Aire 1990; Osuagwuh 1992). No incidence of abortion or stillbirth in LH treatment indicates that the level of feeding was sufficient during late pregnancy to maintain intrauterine foetal survival and neonatal wellbeing. This further suggests that gravid does in LH made compensatory foetal growth when supplemented with pregnancy allowance. It is interesting to note that high level of concentrate fed to gravid does in treatment HH did not have any appreciable benefit over treatment LH particularly in terms of birth weight of kids. Significantly higher birth weight of kids in HH and LH treatments as compared to HL treatment was contrary to the earlier observation in WAD goats (Osuagwuh 1992), but similar to the findings of Dayeh et al (1996). The gestation length of all does was similar irrespective of dietary treatment.

Economics of strategic feed supplementation

The results indicated that if the feeding strategy of treatment LH is followed in comparison to that of treatment HH, a saving of about Rs. 60/- per animal (US $ 1.00 ≈ Rs. 46.00) can be made during the gestation under the conditions of this trial (Table 4).


Table 4.   Economics of strategic feeding (~150 days) of pregnancy allowance

 

HH

HL

LH

SEM

P value

Mean concentrate intake/animal, kg

44.4b

31.2a

33.4a

0.99

0.039

Cost of concentrate*, Rs.

266.1

187.4

200.6

-

-

Mean total wheat straw intake/animal, kg

31.9a

40.2b

36.9b

2.01

0.046

Cost of  wheat straw**, Rs.

31.9

40.2

36.9

-

-

Total feed cost/animal, Rs.

298.1

227.6

237.6

-

-

^ 1 US$  ≈  Rs. 46.00/-

*Cost of concentrate mixture (Rs./kg) = 6/-

**Cost of wheat straw (Rs./kg) = 1/-


Therefore, in economic terms, improvements in productivity due to better nutrition during early phase of pregnancy were small and may not be justified in terms of net returns under small holder farming systems (Sibanda et al 1997).


Conclusions


Acknowledgement

This study was financially supported by funds provides by the Indian Council of Agricultural Research, New Delhi, India.
 

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Received 6 June 2006; Accepted 12 September 2006; Published 1 November 2006

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