Growth of Arbia goat kids in an intensive production system in Setif, Algeria

The growth of 81 indigenous Arbia goat kids reared in an intensive system in Setif in northeastern Algeria was observed between birth and 70 days of age. The kids were dam-raised during the first month and then provided with 150 g/head/day of a total mixed ration and oat hay. The kids’ live weights were assessed at fasting and at different ages: 0, 10, 21, 30, 42, 60, and 70 days. The average daily gains (ADG) were also calculated. Growth results were presented for all kids by sex and litter size. The average birth weight was W0 = 2.53±0.19 kg, while the average weight at 70 days was W70 = 10.1±1.54 kg, which correspond to an overall daily weight gain of ADG0-70 = 108±21 g/day. The study showed that birth weight was affected by litter size, while growth after birth was mainly affected by sex. Birth weights were similar between males and females, but males grew faster (p<0.001) after birth. Single kids were heavier (p<0.05) than twins at 70 days of age, which is the consequence of a heavier birth weight and a faster growth rate in the first 10 days after birth (ADG0-10). After 10 days, litter size did not affect ADG. Compared to other indigenous populations, Arbia goat kids demonstrated valuable growth potential for meat production.


INTRODUCTION
Goat farming in Algeria coincides with the presence of other ruminants in rough, isolated rural areas and constitutes an important source of income for rural households. Goat flocks commonly rely only on pastoral and inedible resources, while feed supplements are provided exceptionally in the winter to ensure the animals' survival (SAHRAOUI et al. 2016). How the goats are reared is especially crucial to balancing and sustaining sheep and cattle farming in order to secure production systems.
The problem with the value chain for goats in Algeria is the increasing consumer demand for goat meat and milk from low-input pastoral production systems. In fact, indigenous goats are mainly reared in suckling systems for meat production. Efforts to develop high-input systems were made only for dairy production with selected imported breeds, without considering the potential of local animals. The only studies which have evaluated the production potential of indigenous populations were conducted in extensive systems (MADANI 2000, BELANTAR et al. 2018, DJOUZA & CHEHMA 2018.
The Arbia goat population is the most widely dispersed goat population in Algeria, and while its morphometric characteristics and genetic diversity have been identified (FANTAZI et al. 2017, TEFIEL et al. 2018, its productivity and resource use efficiency are still relatively unknown. Previous studies ( MAHGOUB et al. 2012, LAOUADI et al. 2018) have shown that meat production is still the main production type for the indigenous Arbia population, which is why growth is important to the profitability of farms. Therefore, this study investigates the pre-weaning growth of Arbia goat kids in highinput systems and the effect of sex and litter size.

MATERIAL AND METHODS
The experiment was conducted on the COOPSSEL Cooperative farm, located in Setif in the northeastern region of Algeria (35°58'N, 5°32'E), which has a semi-arid climate and receives around 400 mm of rainfall per year.
The experiment involved 81 goat kids (Capra hircus) of the indigenous Arbia breed (Figure1) raised in a high-input, zero-grazing system. The goat kids were dam-raised during the first month of age. As of the second month, oat hay and 150 g/head/day of a total mixed ration (TMR) were also provided (Table 1). days, 60-70 days, and 0-70 days. The kids were weighed in the morning before feeding on a 30 kg weighing scale (5 g precision).
The XLSTAT software (version 2014) was used for statistical analysis. For descriptive statistics and a comparison of means, the Student's t-test was used to analyze LW (live weight, kg) and ADG (average daily gain, g/day), based on sex and litter size. Correlation tests were performed to assess the relationship between LW and the different growth periods of the kids. A significance level of 5% was accepted.

RESULTS AND DISCUSSION
Effect of sex: The weight characteristics of Arbia goat kids are presented in Table 2. Results showed that birth weight (W 0 ) was similar (p>0.05) between males and females (2.56±0.2 kg and 2.5±0.17 kg, respectively). The birth weight for males was similar to the values reported by DJOUZA & CHEHMA (2018) for the same breed and by CHENTOUF et al. (2006) for the indigenous goat of Northern Morocco. However, compared to previous studies, the birth weight was higher for females in this study (W 0 = 2.1±0.6 and W 0 = 2.37±0.34, respectively). The average W 0 was higher than the weights recorded for the Draa goat (W 0 = 2.3 kg) reared in the oases of Morocco (IBNELBACHYR et al. 2007), the black and red goats of Maradi (W 0 = 1.95 and 1.82 kg, respectively) in Niger (MARICHATOU et al. 2002), the Lubumbashi goat (W 0 = 1.75 kg) of Congo (KALENGA et al. 2015), and the Creole goat (W 0 = 1.73 kg) (ALEXANDRE et al. 1997). The average W 0 was lower than the weights registered for the selected European breeds Saanen (W 0 = 3.22 kg), Alpine (W 0 = 3.65 kg), and Toggenburg (W 0 = 3.38 kg) (McMANUS et al. 2008) and the Damascus breed (W 0 = 3.92 kg) (GÜNEY et al. 2006).
At 10 days of age, the difference between the sexes was significant (p<0.05); the males weighed more than the females (4.06±0.57 kg vs. 3.54±0.69 kg). The weight at 10 days was significantly higher for both sexes than for the Creole goat (ALEXANDRE et al. 1997). In comparison with CHENTOUF et al. (2006), our results showed a similar weight for males but a lower weight for females (4.1±0.8 Vs 3.3±0.9 Kg). Moreover, for weights W 21 , W 30 , W 42 , W 60, and W 70 , males registered greater values than females (p<0.001). We also found that W 30 and W 70 in both sexes were higher than those observed in the Creole breed (ALEXANDRE et al. 1997), in the northern goat of Morocco (CHENTOUF et al. 2006), and in the Arbia population reared in extensive systems (DJOUZA & CHEHMA 2018). Figure 2 shows that males and females were born with the same weight but that males grow faster. A similar pattern was also reported for the West African dwarf goat and the Croatian multi-colored goat (MIOČ et al. 2011, BIRTEEB et al. 2015), while CHENTOUF et al. (2006 reported that males had a greater birth weight than females in the indigenous goat population of northern Morocco. Based on Figure 2 and Table 3, males had higher ADGs than females (p<0.05), except for ADG 60-70, which decreased significantly for males and was closer to the value for females at this age. On average, the overall ADG (0-70 days) was greater for males (p<0.001) than for females (124±15 vs. 96±17 g/day).  (2006) in high-input systems and higher than the values provided by DJOUZA & CHEHMA (2018) for the same breed in low-input systems. Therefore, for faster growth, a balanced diet is vital for both the lactating does and goat kids.
Effect of litter size: The effect of litter size on the kids' birth weight was clearly demonstrated in our study. Single kids were heavier than twins (Table 4). Our results are consistent with findings by MADIBELA et al. (2002) and ZELEKE (2007) for the Tswana breed of Botswana and the Somali breed of Ethiopia, respectively. The effect of litter size on birth weight is due to the twins' small size and low weight in the uterus resulting from the nutrients shared between fetuses (ROBINSON et al. 1977, LAWRENCE & FOWLER 2002. This difference in birth weight influenced weight at different stages of growth. This was also the case for the Creole goat (CHEMINEAU et al. 1985) and the Croation multi-colored goat (MIOČ et al. 2011). The weights of single and twin goat kids were different (p<0.001) between W 0 and W 10 and partly recovered at W 21 until weaning (Table 3). Growth rate in the pre-weaning period was affected by litter size and was higher for single kids than for twins (p<0.05). These results are consistent with the data provided by MADIBELA et al. (2002), ZELEKE (2007, and BUSHARA et al. (2013) for the Tswana goats of Botswana, the Somali goats of Ethiopia, and the Taggar goats of Sudan, respectively. For the Blended breed of Tanzania, LYATUU et al. (1992) also reported that after birth, single kids had enough milk to develop before weaning, while twins had to fight over their mother's milk. Table 5 shows that the difference between single and twin goat kids is significant only for ADG 0-10 (p<0.01); however, it was significant enough to influence ADG 0-70 (overall), which was more significant for single kids (p<0.05). Figure 3 demonstrates that single kids experienced faster growth (p<0.01) than twin kids during the first 10 days, after which the ADGs of the twin kids increased rapidly during ADG 10-21 to catch up to the single kids' growth rate until finally reaching the same pace of growth. This, however, allowed single kids to maintain a higher weight than twin kids. According to Tables 3 and 4 and Figure 3, the difference in weight at 70 days of age can be attributed to the differences in birth weight based on sex combined with a faster growth rate for single kids during the first 10 days after birth.

Relationship between the weights at different ages:
The growth of goat kids is influenced by several factors that are genetic and/or environmental (ANDRIES 2013, MEZA-HERRERA et al. 2014. Table  5 illustrates that the birth weight's effect on weight at different ages is moderate and regressive. The correlation between W 0 and W 10 is r W0-W10 = 0.56, while the correlation between W 0 and W 70 is r W0-W70 = 0.40.  Table 5 shows that the environment had the most important effect on the goat kids' growth. Their growth is strongly related to the mothers' milk production (quality and quantity), especially during the first 40 days (ALEXANDRE 1991). This means that the effect of their birth weight, which is affected by litter size, on their weight at 70 days of age is moderate. In fact, over time, kids express their genetic potential and can catch up with "compensatory growth." This phenomenon has been observed in multiple litters, as reported in the study on five Mexican breeds by MEZA-HERRERA et al. (2014), who indicated that litter size has no significant effect on weaning weight (13 kg in this case).

CONCLUSION
The Arbia goat has adapted well to controlled breeding conditions and expresses interesting growth patterns compared to several other African breeds (the Draa goat from Morocco, the Maradi from Niger, or the Lubumbashi from Congo). However, as with other goat breeds and other small ruminants, there are many variable factors that modify these growth patterns, including litter size and the sex of the kid, whose effects have been clearly demonstrated in our study.
Our study also showed the importance of a balanced diet in reaching target weights (marketable) more quickly in order to optimize the farm's productivity.
For better animal use and enhanced productivity, improvements can be made. These improvements range from the management of food and livestock farming practices to genetic improvement, which is perfectly desirable in the case of the Arbia goat breed as it has exhibited good growth potential.