Assessing Lactation Curve Characteristics of Dairy Cows Managed under Contrasting Husbandry Practices and Stressful Environments in Tanzania

• Published in: World (Basel) 2022-12, Vol.3 (4), p.1032-1052
• Main Authors: Shija, Dismas Said, Mwai, Okeyo A., Ojango, Julie M. K., Komwihangilo, Daniel M., Bebe, Bockline Omedo
• Format: Article
• Language: English
• Subjects: Agricultural production; Agriculture; Animal lactation; Animals; Breastfeeding & lactation; Cross-sectional studies; Dairy cattle; Dairy farms; Density; Deployment; Disease; Environmental conditions; Farmers; Feeds; Health status; Heat; Humidity; Infections; lactation curve parameters; Livestock; Longitudinal studies; Milk production; Physiology; positive deviants; production environment; Productivity; Scarcity; smallholder dairy farming systems; Stress; Welfare
• ISSN: 2673-4060; 2673-4060
• DOI: 10.3390/world3040059

The ability of smallholder dairy farming systems (SHDFS) to achieve desirable lactation-curve characteristics is constrained or reduced by environmental stresses. Under stressful production environments in the tropics, the better lactation-curve characteristics in smallholder dairy farms are a result of improved dairy genetics and husbandry practices. Better husbandry practices improve animal health and welfare status, which is important to sustain SHDFS in the tropics where dairy cattle are constantly exposed to multiple environmental stresses of feed scarcity, disease infections and heat load. In this case, lactating cows in smallholder dairy farms labelled positive deviants are expected to express lactation curve characteristics differently from typical farms, regardless of the stress levels confronted. Thus, this study tested this hypothesis with Holstein–Friesian and Ayrshire cows in two milksheds in Tanzania classified them into low-and high-stress environments. A two-factor nested research design was used, with farm (positive deviant and typical) nested within the environment. Positive deviant farms were farms that performed above the population average, attaining ≥0.35 Mcal NEL/d energy balance, ≥6.32 L/cow/day milk yield, ≤1153.28 days age at first calving, ≤633.68 days calving interval and ≤12.75 per 100 animal-years at risk disease-incidence density. In this study, a total of 3262 test-day milk production records from 524 complete lactations of 397 cows in 332 farms were fitted to the Jenkins and Ferrell model to estimate lactation curve parameters. In turn, the outcome parameters a and k were used to estimate lactation curve characteristics. The lactation curve characteristic estimates proved the study hypothesis. Regardless of the stress levels, cows in positive deviant farms expressed lactation curve characteristics differently from cows managed in typical farms. The scale (a) and shape (k) parameters together with peak yield and time to peak yield indicated higher lactation performance in positive deviant farms than in typical farms under low- and high-stress environments (p < 0.05). Lactation persistency was higher in positive deviants than typical farms by 14.37 g/day and 2.33 g/day for Holstein–Friesian cows and by 9.91 g/day and 2.16 g/day for Ayrshire cows in low- and high-stress environments. Compared to cows managed in typical farms, cows in positive deviant farms attained higher lactation performance under low- and high-stress; Holst