Other factors influencing economic values

Only a few papers are available in the field of economic analysis of rabbit production in different countries. In some cases, e.g in Ghana or in Tunisia, the rabbit production systems (based on small-scale farms and using local forage etc.) are far from the European conditions. Therefore in this section some Australian and Chinese data showing the effects of age and weight, as well as the importance of CT-based selection will be presented.

29 Australian and Chinese literature

Prayaga and Eady (2000) gave some economic parameters about the „trait economic value” (in Australian Dollar, AUD). If the mortality from weaning to slaughter decreased by 1%, daily weight gain during fattening increased by 1g or daily feed consumption per young rabbit during fattening period decreased by 1g, the economic improvements per doe per year were 3.11, 1.98 and 0.78 AUD.

Rabbit meat prices in China were much lower than in other countries. In 2009 the price of one ton of rabbit meat was 4,509; 4,308; 3,229 and 3,046 USD in Germany, France, Portugal and Hungary, respectively. At the same time in China, it was only 952 USD (Wu et al., 2012). In China, maize was one of major feed grains used by medium- and large-scale rabbit farms. On small farms, local feed resources or agricultural by-products were also used.

Presently in China, rabbits are still mainly raised in smaller units, typically involving a husband and wife raising between 3,000 to 5,000 rabbits per year. Raising rabbits is still labor intensive (Karikari and Asare, 2009), but the cost of labor is also low. The competitiveness of China’s rabbit meat is based on the low price of feed and labor cost. The disadvantage of China is that they are able to export only frozen meat. However, according to Yan et al. (2012) export was not the main business of the China rabbit processing companies. The great demand in China’s domestic market has promoted the rapid total development of the industry. Zilin (2011) and Yan et al. (2012) published some data about the prices in China. The price of one rabbit was about 6.34 USD, the total rearing cost was between 3.17-3.96 USD in smaller farms and 3.33-4.12 USD in farms with 100-500 does: the gross margin per rabbit was from 2.38 to 3.17 USD.

30 Effect of age and weight

When evaluating the economic benefit of rabbit farms, one of the factors is the age and weight of growing rabbits at slaughter. Szendrő K. et al. (2012a) studied the effect of age and weight at slaughter on the value of loin fillet, thigh meat and whole carcass of rabbits. The animals were 74, 84 and 94 days of age at slaughter, with an average body weight of 2.53, 2.84 and 3.15 kg, respectively, and with five weight categories in each age group (Metzger et al., 2011). Within the same age categories, the effect of body weight on the value of the whole carcass, loin fillet and thigh meat was significant in each case. A similar tendency can be seen with the whole carcass, loin fillet and thigh meat with age, but significant differences were observed only between the 74 day rabbits and the two older age groups. The lowest value was achieved at the youngest age or the smallest weight (4.39 and 4.27 €/kg of carcass for the whole and for the total value of parts of carcass, respectively). The highest value was achieved at the oldest age or the heaviest weight (9.10 and 9.31 €/kg of carcass for the whole and for the total valuable parts of the carcass, respectively). The conclusion was that when the values were evaluated, 74-day old rabbits were not mature enough, while 84-day old rabbits were considered favorable for slaughter.

Ramon et al. (1996), Piles et al. (2004a), Larzul and Rochambeau (2004), Metzger et al. (2006a,b) and Szendrő et al. (2009a, 2010) revealed a strong connection between the adult body weight and growth rate. In accordance with the results of several authors (Lukefahr et al., 1982; Gómez et al., 1998; Larzul and Rochambeau, 2004), larger carcasses, carcass parts, and organ weights were found in larger rabbits. Pla et al. (1996, 1998), Gómez et al. (1998), Hernández et al. (2006) compared rabbit lines selected for litter size or growth rate. When carcass traits were compared at the same age the differences for dressing out percentages were lower, compared to the

31

examination when body weight was similar but at different ages. In the latter case, the rabbits of higher adult body weight were less mature at slaughter compared to the examinations made at identical ages. The greater the difference between the adult body weights of the genotypes and the lower the age at slaughter, the greater are the detectable differences for dressing out percentage. Szendrő et al. (2009b) established that the carcass traits of PWhite and PLarge were related to the CT-selection for improving meat in the body.

Breeds, CT-based selection

The choice of breed may also play an important role in the economic aspects. Currently, Pannon breeds and Hycole hybrid are the most prevalent breeds in Hungary (Juráskó, 2014). Hybrids could achieve better production yields, especially in reproductive traits, than purebred lines. However, the parent stock needs to be repurchased every year, thus 120% replacement is expected. In the case of purebred rabbits, the replacement is solved by their own progeny, which is significantly cheaper than purchasing the parent stock. It should also be noted that each new rabbit on the farm may increase the chance of disease occurring, while breeding their own replacements minimizes this risk. PWhite and PLarge breeds have a special advantage for slaughterhouses, since they produce more meat than other breeds and lines as a result of CT-based selection (Matics et al., 2014).

In the selection centers of hybrid companies the maternal lines are selected for improving reproductive performance (litter size at birth or at weaning), and the objective of selection of the sire lines is the weight gain (Baselga, 2004; Garreau et al., 2004; Khalil and Al-Saef, 2008). Generally, carcass traits are not included among the selection criteria. Using CT in selection of

32

rabbits for improving meat volume is a unique in vivo, non-inasive method.

The CT-based selection has been carried out at Kaposvár University since 1992. During the first 12 years, the average surface of Musculus longissimus dorsi (L-value) was measured. In 2004 the L-value was replaced by thigh muscle volume (TMV) which is estimated between the crista iliaca of the os ilium and the patella.

The L-value had moderate heritability (0.33) but this value is higher than the heritability of the thigh muscle volume (0.19-0.25) (Nagy et al., 2006, 2010;

Gyovai et al., 2008, 2012). The genetic trend for the TMV was higher in the PLarge (5.8 cm³) than in the PWhite (4.0 cm³) (Gyovai et al., 2008; Nagy et al., 2013). Using divergent selection, CT-based selection for L-value improved the dressing out percentage by 1.8%, and increased the weight of the mid and hind parts of the carcass (by 5.1 and 2.7%, respectively).

Divergent selection for TMV caused differences in dressing out percentage and meat on hind legs (1.1 and 1.9%, respectively) in the second generation (Szendrő et al., 2012). Based on economic calculations CT-aided selection generates a substantial profit at the slaughterhouse level (Mikó et al., 2010).

Metzger et al. (2006a,b) compared different genotypes and revealed how

Existing publications have mainly focused on evaluating production and carcass traits. Reports on economic evaluation for carcass traits are rare (Mikó et al., 2010; Verspecht et al., 2011; Szendrő K. et al., 2012b). The objective of the Mikó el al. (2010) study was to examine the efficiency of

33

the CT-aided selection from the viewpoint of the slaughterhouses. Using the same selling price for PWhite and Hycole rabbits, the whole carcasses or the meat fillet products resulted in 19 and 43 Hungarian Forint (HUF) per kg extra income for the PWhite rabbits. Supposing a slaughter weight of 2.7 kg this value was 51 and 116 HUF/rabbit. Comparing pure PWhite and PWhite x Hybrid genotypes the advantage of the PWhite rabbits was 38 and 78 HUF/rabbit for whole carcass and the meat fillet product, respectively.

Based on the data of divergent selection for thigh muscle volume, calculated for 10 generations, selling the whole carcass or the meat fillet product resulted in 67.5 and 216 HUF additional income per individual (average body weight of 2.7 kg) for the slaughterhouse, respectively. It can be concluded that the selection based on CT data is highly advantageous for the slaughterhouses because they obtain more lean meat from a CT selected rabbit which results in substantial extra income.

The economic advantage of CT-based selection was also shown in other prediction of weight and composition of four primal cuts of lamb: hind leg, loin, rack and forequarter by using CT in 300 lambs, when the economic benefit of incorporating cut distribution into a breeding program was evaluated. Authors predicted the net benefit from two selection indices for a hypothetical breeding program given a 10-year horizon, and showed higher (1.02 million New Zealand Dollar, NZD) net benefits when selection was for composition of cuts and fat rather than selecting for weight of lean and

34

against fat in the carcass. Jopson et al. (1996) estimated the marginal economic benefit of incorporating CT into a terminal sire sheep breeding program. For a single year’s investment (i.e. one year’s CT scanning) the cumulative net present value was positive by year three (evaluation occurred in year zero) and was nearly maximal by year ten.