Effect of electronic identification with ruminal bolus on growth parameters and stomach development in young goat kids

Abstract

Although most of the European goat farms are dairies, there are a significant number of herds dedicated to meat production as the main product. Due to the current policy of food safety in European Union, the traceability, particularly the electronic identification, is taken into consideration; however, the effect of this electronic identification has not been studied on goat kids for fattening. For this reason, the effect of the ruminal bolus on the growth of goat kids and the development of their stomachs were studied. At 16 kg, animals were randomly assigned in two groups: control (n=23) and bolus (n=27), the latter identified with Inoxeramic Bolus. Both of them were slaughtered at 24 kg. Statistical differences in growth parameters and stomach development were not observed, except in the reticulum-omasal orifice diameter, which was bigger in the bolus group. Moreover, when the breed was taken into account (Majorera, Palmera and Tinerfeña), interbreed differences were found in orifice diameter and empty rumen–reticulum weight, due to treatment (P<0.05).

Keywords:

• goat
• bolus
• ruminal
• carcass
• identification

Introduction

Although most of the European goat farms are dairies, there are a significant number of herds dedicated to meat production as the main product. Due to the current policy of food safety in European Union, the traceability, particularly the electronic identification, is taken into consideration. It has been reported that animals are affected by several factors including genetic (Yildirm et al. 2009), nutrition (McMurphy et al. 2009; Montano et al. 2010, Lopez et al. 2010; Argüello 2011) hormones (Aslaminejad et al. 2010; Liu et al. 2010), stress (Hernández-Castellano et al. 2011) and others. Nevertheless, the use of ruminal bolus for bovine, caprine and ovine identification has been developed without negative results (Caja et al. 1999; Garín et al. 2000; Carne et al. 2009, 2011; Castro et al. 2010). Visible injures in the rumen–reticulum of cows have not been observed (Hasker and Bassingthwaite 1996), and neither have been seen to have any effect on growth of lambs (Garín et al. 2003). To complete this research, it has been considered necessary to study the effects of electronic identification on goat kids for fattening.

Material and methods

The present study was performed at the Instituto Canario de Investigaciones Agrarias (Tenerife, Spain) on a group of 50 goat kids (9 Palmera, 17 Majorera, 24 Tinerfeña); all of them having been kept under the same feeding conditions, following the experimental animal procedures. Newborn goat kids were reared with their mothers for 9 weeks. When they weighted 16 kg they were randomly assigned into two groups [bolus group (BG) n=27 and control group (CG) n=23]. The BG goat kids were identified with Inoxeramic Bolus (diameter 1.64 cm, length 6.7 cm and weight 51 g) which was introduced with an applicator. Both groups had external identification. The reader used was Gesreader 25 (Gesimpex Comercial, S.L., Barcelona, Spain, ISO 11784 and 11784 of UE). In order to evaluate their growth until slaughter (approximately 24 kg), animals were checked and weighed weekly. After slaughter, bolus was removed and physical-anatomical parameters of the stomach were measured: empty rumen–reticulum weight, empty omasum–abomasum weight and the reticulum-omasal orifice diameter. Carcass yield (CY) was calculated according to Sierra (1970). The effect of treatment and breed on growth and stomach development were analysed with the GLM procedure (SPSS 11.0 for Windows, SPSS Inc., Chicago, IL) using age at slaughter as a covariant and executing a multivariate analysis of variance to obtain the significance level.

Results and discussion

All boluses were recovered in the slaughter house. Boluses were found in the reticulum in 81.5% of animals, being lower than the results showed by Ghirardi et al. (2007) with the same kind of bolus in lambs (89.2%), but within the range of values reported in ovine for different electronic bolus models (Caja et al. 1999; Garín et al. 2005). However, Castro et al. (2010) showed a lower retrieval bolus percentage from the reticulum in goat kids, ranging from 0 to 7%, the greater majority of boluses being located in the rumen (from 93 to 100%), probably due to the use of younger animals. Goat kids were slaughtered at 169 ± 2.10 days at 24.3 ± 0.16 kg. Table 1 illustrates the effect of bolus on growth parameters. Majorera goat kids (control n = 8; bolus n = 9), weaned at 12.74 ± 0.32 kg, showed statistical differences (P< 0.05) in the average daily gain (ADG) between weaning and slaughter, due to treatment and growth which were slower in the identified animals (application at 16.81 ± 0.81 kg). Nevertheless, the ADG from birth to slaughter was not affected by treatment in any of the study breeds, although it was slightly less in BG. This implied that slaughter took place when they were older. These results are in accordance with those reported by Garín et al. (2003), in which growth at weaning and fattening time was not affected by bolus in Manchega lambs. There were no significant differences due to the breed effect in all growth parameters. No differences have been found of the effect of bolus on CY.

Table 1. Effect of the bolus (Inoxeramic, 51 g) on growth parameters.

	CG	BG	SEM
ADGWS (g)
Majorera	122.95^a	104.37^b	5.98
Palmera	99.45	100.99	8.25
Tinerfeña	112.86	104.99	5.08
Total	111.76	103.45	3.80
ADGBS (g)
Total	126.38	122.12	2.51
CY%
Total	48.83	48.17	1.09
Note: Superscript ‘a’ and ‘b’ mean significant differences between groups (P < 0.05).
SEM – standard error of means; CG – control group; BG – bolus group; ADGWS – average daily gain between weaning and slaughtering; ADGBS – average daily gain between birth and slaughtering; CY – carcass yield.

Table 2 shows the treatment effect on the physical stomach parameters. The reticulum-omasal orifice diameter was seen to be affected by the treatment in goat kids from Majorera breed (P < 0.05), being bigger in BG. With regard to this parameter, the bolus caused significant interbreeding and also caused differences when the three breeds were analysed together. Although the reticulum-omasal orifice was greater than the Inoxeramic Bolus diameter, no bolus went into the abomasums. These results are in accordance with Ghirardi et al. (2007), in lambs who use the same bolus prototype and Ghirardi et al. (2006) in bovine where the reticulum-omasal orifice was also greater than the diameter of the bolus used. The empty rumen–reticulum weight was found to have statistical differences in the Majorera breed (P< 0.05), disappearing when considering all breeds together. These results contrast with those found by Garín et al. (2003), who did not find differences in this parameter due to the presence of bolus in fattening lambs slaughtered at 24 kg. This could be explained by the fact that a heavier bolus was used in this experiment and there was a longer period of time until slaughter (81.66 ± 17.8 days).

Table 2. Effect of the treatment (control vs. bolus) on anatomic parameters of digestive system.

	CG	BG	SEM
ROOD (cm)
Majorera	2.260^a	2.556^b,x	0.077
Palmera	2.340	2.100^y	0.106
Tinerfeña	2.310	2.548^x	0.093
Total	2.296^a	2.496^b	0.058
ERRW (kg)
Majorera	0.650^a	0.782^b,x	0.035
Palmera	0.612	0.595^y	0.039
Tinerfeña	0.692	0.696^z	0.025
Total	0.659	0.708	0.020
EOAW (kg)
Majorera	0.270^x	0.284	0.017
Palmera	0.330^a,xy	0.260^b	0.017
Tinerfeña	0.356^y	0.323	0.015
Total	0.316	0.301	0.011
Note: Superscript ‘a’ and ‘b’ mean significant differences between groups (P < 0.05). Superscript ‘x’, ‘y’ and ‘z’ mean significant differences between breeds (P < 0.05).
SEM – standard error of means; CG – control group; BG – bolus group; ROOD – reticulum-omasal orifice diameter; ERRW – empty rumen–reticulum weight; EOAW – empty omasum–abomasum weight.

The empty omasum–abomasum weight showed small differences among breeds in CG, being particularly smaller in the Majorera breed. This could be related to the younger age at slaughter of Majorera group and because the weight at slaughter was the same for all of them. Statistical differences in full stomachs were not taken into account because of the high variability of results which were obtained, and the fact that the empty weight of the stomach is an objective parameter which is clearly related to the development of the stomach.

In conclusion, it can be considered that the electronic identification with Inoxeramic Bolus in goat kids slaughtered at approximately 24 kg did not produce any important effect on the growth parameters and the stomach development, and therefore, can be considered as a valid method for tracing goat meat.

Acknowledgements

Research was supported by the European Commission, 5th Framework Program, Quality of Life and Management of Living Resources, contract QLk1-2001-02229 (EID + DNA Tracing), and by the Spanish Ministry of Education (Plan Nacional I + D + i; project AGL-2007-64541).