Phenotypic and Genetic Analysis of Total Milk Yield in Holstein-Friesian Cattle under Libyan Conditions

Abousaq, F. M; Alzaqouzi, A.A; Eisa, F.M; Al-Zorqani Z. A

Authors

Abousaq, F. M Department of Animal Production - Faculty of Agriculture - University of Tripoli Author
Alzaqouzi, A.A Department of Animal Production - Faculty of Agriculture - University of Tripoli Author
Eisa, F.M Higher Institute of Science and Technology- Soq AlkamisMsehel- Libya Author
Al-Zorqani Z. A Department of Animal Production - Faculty of Agriculture - University of Tripoli Author

Keywords:

Total milk yield, Heritability, Variance components, Holstein-Friesian, Libya

Abstract

This study aimed to estimate the phenotypic and genetic factors for total milk yield (TMY) in Holstein-Friesian cattle under Libyan conditions, assess the contribution of different factors to the total variance, and estimate heritability to guide future selection programs. Data were collected from 979 production records of Holstein-Friesian cows at the Ghout Sultan Agricultural Project, eastern Libya, between 1985 and 1998. A mixed linear model was applied including random effects (sire, dam, lactation period) and fixed effects (month of calving, year of calving, parity). Variance components were estimated using the REML (Restricted Maximum Likelihood) method as implemented in the MIXED procedure of SAS. Heritability (h²) was calculated from variance components. The mean TMY was 9180.46 kg with moderate phenotypic variability (CV = 26.22%). Lactation period, year of calving, and parity had highly significant effects on TMY (P < 0.0001), while month of calving showed a marginal effect (P = 0.07). Sire and dam effects were not statistically significant (P > 0.05). Sire variance was 366,551.4, dam within sire variance was 1,235,646.1, and error variance was 4,305,434.8. The heritability estimate for TMY was 0.248, indicating that about 24.8% of the phenotypic variation is due to additive genetic effects. It was concluded that lactation period, year of calving, and parity significantly affected TMY, while month of calving showed a marginal effect. Sire and dam effects were not significant, likely due to reliance on imported, non-adapted semen. Genetic improvement is feasible under Libyan conditions; however, establishing a locally adapted breeding program using proven sires is recommended.it concluded that

Downloads

Download data is not yet available.

References

1) Ajili, N., Rekik, B., & Ben Gara, A. (2007). Genetic and phenotypic parameters of milk production in Tunisian Holsteins. Livestock Research for Rural Development, 19(2), Article #26.

2) Ammar, H., Al-Dobaib, S. N., & Ahmed, M. (2024). Genetic and phenotypic trends for milk production traits in Holstein-Friesian cattle under arid conditions. Tropical Animal Health and Production, Vol. 56, Issue 3, pp. 89-104.

3) Boujenane, I., & El Hazzab, A. (2020). Genetic and non-genetic effects on milk production traits of Holstein cattle in Morocco. Tropical Animal Health and Production, 52(5), 2429-2435.

4) Falconer, D. and Mackay, T.1996. Introduction to Quantitative Genetics. 4th ed., Long man, London and NY.

5) Hammami, H., Rekik, B., & Gengler, N. (2009). Genotype by environment interaction in dairy cattle in Tunisia. Animal, 3(4), 485-493.

6) Kaya, I., Akbulut, Ö., Tüzemen, N., & Bayram, B. (2024). Genetic Evaluation of Milk Yield and Components Using Random Regression Models in Holstein Cattle. Journal of Animal Bioscience, Vol. 37, Issue 2, pp. 245-258.

7) Khattab, A. S., & El-Barbary, A. S. A. (2019). Factors affecting milk production in Holstein cows under Egyptian conditions. Egyptian Journal of Animal Production, 56(2), 87-94.

8) Miller, A. J., Santos, J. E. P., & Rhoads, R. P. (2025). Climate Change and Dairy Productivity: Modeling the impact of Temperature-Humidity Index (THI) on Total Milk Yield in Holstein Friesians. Journal of Dairy Science, Vol. 108, Issue 1, pp. 512-527.

9) Niyigena, V., Mashingo, M., & Kim, S.-S. (2025). Management factors affecting milk yield, composition, and quality on smallholder dairy farms. Scientific Reports (Nature Portfolio), Vol. 15, Article No. 1120.

10) Ojango, J. M., & Pollott, G. E. (2001). Genetics of milk yield and fertility traits in Holstein-Friesian cattle on large-scale Kenyan farms. Journal of Animal Science, 79(7), 1742-1750.

11) Rafeeq, M., Tariq, M. M., Bajwa, M. A., & Rashid, N. (2016). Effect of non-genetic factors on milk yield and lactation length in Holstein Friesian cattle under subtropical conditions. Journal of Animal and Plant Sciences, 26(3), 618-624.

12) SAS Institute Inc. (2002). SAS White Papers. Cary, NC: SAS Institute.

13) Thompson, R., Main, D. C. J., & Mullan, S. (2026). Could living space provision in the first lactation have long term effects on milk production in housed dairy cows? Frontiers in Animal Science, Vol. 7, Article 109842.

14) Wilson, P., Garnsworthy, P. C., & Ferris, C. P. (2024). Lactation performance of Holstein dairy cows fed diets with or without an annual forage mix silage. Translational Animal Science, Vol. 8, Issue 1, pp. 45-60.