Progesterone injection and restricted suckling access could shorten postpartum intervals in traditionally managed West African dwarf goats

S I Ola and G N Egbunike*

Department of Animal Science, Obafemi Awolowo University, Ile-Ife, Nigeria

sola@oauife.edu.ng

*Department of Animal Science, University of Ibadan, Ibadan, Nigeria

Abstract

The potential of restricted suckling access and progesterone injection post partum as a remedy to extended parturition intervals in traditionally managed West African dwarf (WAD) goats was investigated in this study. At 21 days postpartum 36 confined WAD does with synchronised breeding were assigned equally to one of 3 treatments: i) suckling access restricted to between 0900 h and 1700 h; ii) suckling access restricted to between 1700 h and 0900 h the following day and; iii) unrestricted suckling access. At 28 days postpartum each treatment group was further divided into two and one group was given 100 mg im injection of progesterone. Another 14 does on the free range management system with unrestricted suckling access period were also divided into two and a group was also given 100 mg im injection of progesterone.

Kidding interval (KI) was longer in the group with unrestricted suckling access, but in the groups that received progesterone injection KI was significantly (P<0.05) reduced by 27 and 45 days in the confined and free range goats, respectively. Reducing suckling access period to 0900 h - 1700 h appeared to reduce KI without a negative effect on the performance traits of the suckling kids.

These two approaches could be useful to reduce the breeding interval in traditionally managed WAD goats.

Keywords: parturition intervals, progesterone, suckling access restriction, WAD goats

Introduction

Parturition or breeding intervals appears to be the most important reproductive parameter that determines the female livestock productivity (Hofs et al 1985). The average kidding intervals in traditionally managed West African dwarf (WAD) goats is put at about 240 days (Otchere and Nino 1976; ILCA 1981; Ebozoje and Ikeobi 1998). However when critically examined by taking cognizance of the weaning period and survivability of the kids, most WAD does under the natural breeding conditions of traditional management system effectively kid only once in a year (Oppong and Yebuah 1981; Egbunike et al 1993; Gall 1996). This rather long parturition interval constitutes a major limitation to higher reproductive efficiency of the WAD goats.

The parturition interval could be shortened by controlling the frequency or intensity of suckling the postpartum dam (Lawson et al 1984; Grinwich and Mckay 1985; Bell et al 1998; Diskin et al 2001). It was further shown that progesterone (P₄) treatment during the restricted suckling period further aids the early postpartum return and detection of oestrus (Mandiki et al 1995; Diskin et al 2001). This approach appears rather cheap and simple enough to be adoptable in smallholder goat keeping which constitute over 90 % of goat production in Nigeria. Thus in this study we determined the effects of suckling access restriction and progesterone injection postpartum on the return to oestrus and kidding interval in WAD goats.

Materials and methods

Animal management and experimental treatments

Thirty six (36) WAD goat does confined permanently to the pens on-station and another 14 does under scavenging/free range condition on-farm were monitored between March 2002 and March 2003 for this study. The confined goats were housed in the goat barns of the Obafemi Awolowo University Teaching and Research Farm, Ile-Ife, Nigeria and stall-fed ad libitum in groups of 6 animals on a forage combination of Panicum maximum, Gliricidia sepium and Leucanea leucocephala and occasional concentrate supplementation at 150 - 200 g/head/day. The free range goats were owned by different farmers at Kajola village located along Ede road about 6 km from the university farm. At the start of the study the free range does were at different stages of gestation whereas breeding was synchronised in the confined goats. On kidding the scavenging does suckled their kids without restriction until weaning of kids at a standard 5.5 kg liveweight or 13 weeks of age. The confined does on the other hand were allowed to suckle their kids unrestricted only for the first 21 days post-kidding after which they were assigned to one of the experimental treatments below (12 does per treatment).

• suckling access restricted to between 0900 h and 1700 h
• suckling access restricted to between 1700 h and 0900 h of the following day
• unrestricted suckling access

From 8 days post-kidding the confined dams were exposed to buck teasing 3 times daily while the free range dams were assumed to be under uncontrolled buck teasing post kidding. At 28 days postpartum the 3 groups of confined goats and one group of free ranging goats were separately divided into two groups and a group received 100 mg im injection of progesterone (P₄) oil suspension (Long life, China). Buck teasing continued until pregnancy was confirmed. Does were then monitored until next kidding while the kids were also monitored until weaning. In the restricted suckling groups apron linen was tied round the belly, including the udder, of the doe to prevent access to the teats by the kids during the hours of suckling restriction.

Data collection and analysis

In the confined groups postpartum oestrus was monitored with the aid of aproned bucks introduced 2 or 3 times everyday. Does in oestrus were removed and hand mated. For the free range does, day of postpartum oestrus and conception was taken to be 150 days preceding the kidding date. Growth performance of suckled kids was also monitored during the experimental period. Data on the reproductive performance of the does as well as the preweaning performance of the kids were compared separately between the two groups of free range goats and the six groups of confined goats using the t-test and factorial analysis of variance of SAS 2000 software, respectively.

Results and discussion

Productivity of free range WAD does after postpartum progesterone injection

The parameters of productivity monitored during the study are litter size and weight at birth and weaning, weaning age, growth rate, kid's survivability to weaning and kidding interval. Reproduction rate was calculated as kids per year while the productivity index was expressed as kg weaned per doe per year according to the formula of Hofs et al (1985). Table 1 shows the effect of postpartum P₄ injection on these productivity parameters in free range does exposed to unrestricted suckling access period. Except for reproduction rate and productivity index all the other parameters reported were the average of the kidding after P₄ treatment with the individual does or kids as replicate.

Birth weight, growth rate and weaning weight were higher (P<0.05) in free ranging kids whose dams were not supplemented with P₄ postpartum. This also resulted in the lower weaning age (66.23 ± 4.46 days) of this group.

More kids (75 %) survived till weaning period from dams that received P₄ injection compared to 68 % in the group without P₄ injection. Except for litter size in which case hormonal balance may probably be shifted to favour higher ovulation rate, a single i.m P₄ injection 28 days postpartum will not likely have any effect on the subsequent kid's birth and weaning weights, growth rate and survivability. These parameters are strictly related to the nutrition and management of the kids (Odubote et al 1993). Thus P₄ injection to postpartum dam can possibly not be used to explain the performance characteristics of the kids.

Conception and kidding rates were 100% in both groups of dams because only the 14 dams that remained till the end of study out of the initial 18 does were included in the analysis. As common under the free range system, the rest 4 were lost to motor accident and other undetermined causes. The kidding interval significantly reduced by 45 days in the dams that received 100 mg P₄ injection. This result agreed with those of Mandiki et al (1995) in Texel ewes and Diskin et al (2001) in beef cows. The former had shown that single-suckling ewes that received 210 mg of P₄ through the intravaginal device between days 4 and 16 postpartum had earlier return to oestrus of 23 days postpartum compared to 37 days in the control. They further explained that LH pulse frequency was decreased during the period that P₄ intravaginal device was in place but increased significantly one day after its removal. PGF_2α concentration was also lowered in the treated ewes compared to the control.

The reduced kidding interval and higher litter size at birth and weaning (survival rate) accounted for the higher reproduction rate and productivity index in the P₄ injected group since the kid's birth and weaning weights as well as growth rate were lower in this group compared to the non-injected group. Hofs et al (1985) showed that a 20-day reduction in kidding interval of WAD goats alone will produce as much as 11.6 % increase in productivity while a 0.1 more kid will result in about 5.5 % increase in productivity. Thus it could be said that reproduction rate and productivity were better in the P₄ injected dams principally due to the reduction in the kidding interval.

Productivity of WAD does under suckling access restriction and progesterone injection

In Table 2 the same parameters of productivity were reported for the goats whose kids were subjected to suckling access restriction period. Although visual and physical contact between the dams and their kids were maintained during the suckling restriction period, the contact between the kid's mouth and the dam's teat (suckling act) was broken.

Suckling act normally results to increased peripheral prolactin level which would inhibit oestrogen secretion and postpartum oestrus resumption (Hafez 1985).Of particular importance to our study is the effects of these treatments on the postpartum intervals. The average kidding interval in the does with restricted suckling access were shorter than those with unrestricted suckling access. Soon after weaning of the kids, conception occurred earlier in the restricted suckled does (6 - 22 days postweaning) than in the unrestricted suckled does (14 - 41 days postweaning). This observation agreed with those of Lawson et al (1984), Bell et al (1998) and Diskin et al (2001). Mandiki et al (1995) further showed that P₄ treatment on postpartum dams was more effective in its effect in the dry (or non-suckling) ewes than suckling ewes while Diskin et al (2001) reported that a short P₄ treatment coupled with restricted suckling allows oestrus to be expressed during first postpartum ovulation and also eliminates the short oestrus cycle in postpartum cows. However in our study the P₄ treatment did not affect the kidding interval in the does allotted to restricted suckling access as it did in the unrestricted suckling groups (Figure 1).

The higher litter size at birth in the unrestricted without P₄ group could have resulted in longer postpartum interval but there was also higher kid mortality (0.67 survival rate) in this group which could favour earlier resumption of postpartum oestrus (Oppong and Yebuah 1981). Nevertheless we assume that the restricted does with no obvious oestrus response to P₄ injection either did not exhibit oestrus earlier or the oestrus was not detected during the checking periods.

Another possibility for lack of oestrus detection could be the interference from the kids during the teasing periods. We observed that the does were more interested in their kids that were equally trying unsuccessfully to locate the hidden teats during the same period. Diskin et al (2001) showed that calf isolation plus restricted suckling led to a more rapid return to postpartum oestrus than restricted suckling alone. Unfortunately in our study the hormonal profiles (P₄ and LH pulses) of the dams which could provide physiological explanation could not be determined.

Conception and kidding rates of the dams after P₄ treatment were 100% most likely as a result of the better health care which the animals received under confinement. Also all the dams survived the one year that the experiment lasted. Does were continually teased until pregnancy was confirmed.

The reproduction rate appeared to be more related to the variation in the kidding interval as earlier observed by Hofs et al (1985).The calculated productivity index improved when the dams were injected with P_4. We are however cognisance of the low number of animals involved in this study which prevents a conclusive statement on reproduction rate and productivity index. However the results are still relevant as a basis for a larger scale trial.

As mentioned earlier in the text P₄ treatments in this study probably could not be used to explain variations in birth weights, litter size, weaning weight and age and kid survivability. These parameters are better accounted for by the nutrition which both dam and kid received.

Conclusions

• Unrestricted suckling access to kids prolonged kidding interval in confined WAD goats.
  
  
• The kidding interval appeared to reduce when 100 mg P₄ injection was given at 28 days postpartum in the unrestricted suckled dams but not in restricted suckled dams.
  
  
• Kids given suckling access between 0900 - 1700 hrs appeared to gain weight comparable to those given unrestricted suckling access.
  
  
• Restricting suckling access period to 0900 - 1700 hrs appeared to reduce kidding interval without a negative effect on the performance traits of the nursing kids.
  
  
• Although a general and affirmative conclusion from this study may not be sound because of the low number of animals involved, the preliminary indication is that progesterone injection and restricted access to suckling has the potential to shorten postpartum intervals in WAD goats.
  

References

Bell D J, Spitzer J C and Burns G L 1998 Comparative effects of early weaning or once-daily suckling on occurrence of postpartum oestrus in Primiparous beef cows. Theriogenology 50:707 - 715.

Diskin M G, Mackkey D R, Stagg K, Roche J F and Sreenan J M 2001 Shortening the interval to the resumption of ovarian cycles in post-partum beef cows. Teagasc beef production series No 25. Teagasc AFDA, Ballsbridge, Dublin.

Ebozoje M O andIkeobi C O N 1998 Colour variation and reproduction in the West African dwarf goats. Small Ruminant Research 25:125-130.

Egbunike G N, Akusu M O and Carew B A R 1993 Vital reproductive statistics of the West African Dwarf does. In: Goat production systems in the humid tropics, proceedings of an international workshop, Ayeni A O and Bosman H G (editors), Pudoc, Wagenigen, p208-212.

Gall C 1996 Goat breeds of the world. CTA. - Weikerersheim / Margraf, 186p.

Grinwich D L and Mckay R M 1985 Effects of reduced suckling on days to estrus, conception during lactation and embryo survival in sows. Theriogenology 23:449 - 459.

Hafez E S E 1985 Reproductive cycles. In: Reproduction in farm animals. Hafez E S E (editor) p 107 -129.

Hofs P, Montsma G and Nabuurs S 1985 Growth and reproduction rates of West African Dwarf goats under high level of feeding and management. In: Sheep and goats in humid West Africa. Proceedings of the workshop on small ruminants production systems in the humid zone of West Africa. Sumberg S and Cassaday K (editors) p 25-28.

ILCA 1981 Rural sheep and goat production in the forest and savannah belts of Oyo state, Nigeria. ILCA, Addis Ababa, 29 pp.

Lawson J L, Forrest D W and Shelton M 1984 Reproductive response to suckling manipulation in Spanish goats. Theriogenology 21:747 - 755.

Mandiki S N M, Bister J l and Paquay R 1995 Effects of hormonal manipulation on the postpartum reproductive activity in Texel ewes. Theriogenology 40:607 - 620.

Odubote I K, Akinokun J O and Ademosun A A 1993 Production characteristics of WAD goats under improved management system in the humid tropics of Nigeria. In: Goat production systems in the humid tropics, proceedings of an international workshop, Ayeni A O and Bosman H G (editors), Pudoc, Wageningen, p202 - 207.

Oppong E N W and Yebuah N M N 1981 Some production traits of the West African Dwarf goat. Tropical Animal Health and Production 13:208 - 212.

Otchere E O and Nimo M C 1976 Reproductive performance of West African dwarf goat. Ghana Journal of Agricultural Science 9:57-58.

Received 28 November 2006; Accepted 18 April 2007; Published 1 May 2007

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