The analysis of 88 Holstein herds showed significant variation in dairy productivity, highlighting the influence of herd size and management. Table 1 presents key parameters: TMY, standardized 305-day 305-dMY, MFY, FC and LD. High variation coefficients for 305-dMY (24.63%), TMY (26.23%) and MFY (25.75%) indicate notable disparities in milk quantity and composition. The standardized 305-day milk yield averaged 6596.66±1624.99 kg, with an MFY of 242.18±62.36 kg and FC of 3.70±0.53%. The TMY was 7052.19±1849.68 kg over 324.92±42.93 days, aligning with dairy studies in varied environments
(Adediran et al., 2010 ;
Pishchan et al., 2021).
Herd size and production
ANOVA results (Table 2) reveal a highly significant effect of herd size (HS) on all production parameters (p<0.001), except for lactation duration (LD), which remains significant (p<0.01). Larger herds consistently showed higher yields, with those exceeding 150 cows achieving the highest total milk yield (TMY) at 7360.86 kg. Herds with 90-150 cows followed closely, averaging 7134.66-7186.51 kg. In contrast, the smallest herds (HS≤30 cows) had the lowest TMY at 6554.44 kg, highlighting a strong positive correlation between herd size and productivity. Milk yield variation was substantial across herds. Over a standardized 305-day lactation, production ranged from 3909.23 kg to 8460.52 kg. The standardized 305-day milk yield (305-dMY) also varied significantly (p<0.001) across herd size classes, increasing from 6095.92 kg in small herds to 6894.98 kg in large herds (HS>150 cows). However, an exception was noted in the 120-150 cows category, where the average 305-dMY slightly declined to 6698.28 kg. These findings confirm that herd size is a key factor in production efficiency, with larger herds benefiting from economies of scale but potentially facing diminishing returns at certain thresholds.
A detailed analysis of fat yield and lactation length further confirms the impact of herd size on production parameters. Larger herds recorded higher standardized 305-day fat yields (305-d MFY), though they exhibited slightly lower fat percentages and shorter lactation durations. Herds with more than 150 cows achieved an average 305-d MFY of 242.33±1.39 kg but had a lower fat content (FC) of 3.65%. In contrast, smaller herds (HS£30 cows) produced the lowest fat yield (229.66 kg) but with a higher FC of 3.79%, despite their lower standardized milk yield (6095.92 kg). The moderate decline in fat content as herd size increases suggests that larger herds may prioritize milk volume over composition, influencing overall fat percentages. These findings highlight a trade-off between quantity and composition, emphasizing the need for balanced herd management strategies to optimize both production and milk quality.
Variability within herds and comparative analysis of herd size
Significant variability within herd categories highlights the impact of genetics, microclimatic conditions and farm-specific management. Fig 3, illustrates the influence of herd size on production across the 88 analyzed herds. While larger herds generally achieve higher productivity, production values vary, suggesting that optimizing feeding, housing and health management could further enhance yields. Despite fluctuations, overall productivity remains high, indicating that smaller farms could benefit from adopting efficient practices from larger operations. Milk production among Holstein cows shows substantial variability, with highly significant differences between herds (p<0.001). Herd size is the primary factor driving these variations, influenced by genetic potential, environmental conditions and farm management strategies. Management decisions-such as feeding, reproduction and health systems-play a crucial role in determining milk yield. Large-scale farms (>150 cows) consistently outperform smaller herds (≤90), underscoring the importance of modern dairy farming techniques. These farms use intensive rearing systems, housing cows in well-ventilated free-stall barns with high-structure paddocks, shielding them from drafts and extreme heat. Additionally, misting systems help regulate temperature, mitigating heat stress and improving overall productivity.
HS significantly influenced Lactation Duration (LD) (p<0.01), with values ranging from 309.30 to 348.73 days. Smaller herds (HS≤30 and 30<HS≤60 cows) had longer lactations (326.75 and 326.56 days), while larger herds (HS≥120 cows) had shorter durations (≈324 days). Small farms extend lactation, though total milk yield depends more on lactation peak than persistence. Feeding management also plays a key role, as cows in well-managed large farms achieve higher yields than those in smaller, subsistence-oriented farms. TMY varied significantly (p<0.001), with herd size playing a major role (p<0.001). TMY ranged from 4233.76 kg to 9012.57 kg, consistently increasing with herd size. Smaller herds (HS≤30 and 30<HS≤60 cows) recorded lower TMY (6554.44 kg and 6839.91 kg), while medium and large herds (HS≥90) produced significantly more (7134.66-7360.86 kg). These results highlight the impact of herd size on production efficiency, reinforcing the benefits of well-equipped, intensive management systems in larger farms. Despite longer lactation durations in smaller herds, production differences stem from management practices. Cows in small herds (HS≤30 and 30<HS≤60 cows) had higher average calving ages of 45.34 and 46.53 months, compared to 42.09 months in large herds (HS≥150). This suggests that large farms optimize productivity by continuously renewing their herds with younger, high-yielding heifers. Older cows negatively impact herd productivity and economic efficiency, reinforcing the advantage of herd renewal strategies in larger, well-managed dairy operations.
Herd size (HS) significantly influenced standard milk yield (305-dMY) (p<0.001), with values ranging from 3724.77 to 8946 kg per 305-day lactation. Small herds (HS≤30) were the least productive (6279.56 kg), while large herds (HS≥150) peaked at 7075.12 kg. However, 305-dMY declined in the 120-150 cows category (6818.78 kg) compared to the 90-120 class (6886.92 kg), likely due to higher calving ages (47.87 vs. 42.64 months). Fat yield (MFY) also varied significantly (p<0.001), increasing with herd size and peaking at 255.30 kg in medium-sized herds (120≤HS<150 cows).
After peaking, fat yield declined in large herds (HS≥150) to 242.33 kg. Smaller herds produced less fat but had higher fat content (3.79%) than large herds (3.54%). This difference stems from lower milk production (305-dMY: 6279.56 kg vs. 7075.12 kg). High FC with low milk yield suggests energy deficiencies, metabolic disorders, or imbalanced feed. Nutrition plays a key role in milk composition
(Delaby et al., 2003; Cobanoglu et al., 2017). Milk fat percentage depends on concentrate type, feed preparation and distribution. Specific feedstuffs like corn silage and sugar beets enhance FC (
Hoden and Coulon, 1991). Small farms should optimize feed management to improve milk quality.
Implications for dairy farm management
A detailed analysis of herd size categories revealed significant differences (p<0.001) in most production parameters, except lactation length (p<0.01). Herds with 90-120 and 120-150 cows achieved yields similar to larger herds (HS>150 cows), indicating that intermediate-sized herds can perform at levels comparable to large herds. Large herds benefit from optimized management practices, such as free-stall housing and thermal regulation, which mitigate environmental stress. Smaller herds often lack these due to financial or logistical limitations. These findings align with previous studies (
Miciñsk and Pogorzelska, 2010;
Adediran et al., 2010; Satashia and Pundir, 2021), showing larger herds tend to have higher yields, especially in regions with proper infrastructure and herd management. However, productivity gains in large herds must be balanced with animal welfare, as intensive systems often face health challenges. Farms in semi-arid regions like Souss-Massa should implement advanced cooling systems to reduce heat stress for herds exceeding 150 cows. Additionally, targeted management practices like selective breeding and tailored nutrition can enhance productivity while ensuring animal well-being.
This study highlights the significant role of herd size in determining milk productivity, aligning with broader research that links larger herds to higher yield and efficiency. The positive correlation between herd size and milk yield is consistent with studies by
Adediran et al., (2010) and
Doyle and Kelly (1998), which show that larger herds often support greater output due to economies of scale and better management (Chanda
at al., 2022). Larger herds benefit from specialized infrastructure like free-stall housing and ventilation, which is particularly advantageous in semi-arid regions like Souss-Massa, where thermal stress limits productivity (
Mader and Davis, 2004;
Talbi and EL Madidi, 2015). Significant variations (p<0.001) were observed in milk yield, fat yield and lactation length across herd sizes, indicating the productivity advantages of larger herds. As
Grohn et al., (2020) and
Santschi et al., (2011) found, larger herds benefit from advanced management and nutrition, leading to higher yields. However, while herds over 150 cows achieved higher total yield, a slight decline in milk fat percentage was observed, likely due to a focus on milk volume
(Krystallis et al., 2009). Smaller herds maintained more consistent fat content
(Hill et al., 2009).
These findings suggest that while larger herd sizes boost milk volume, they require specific management adjustments to maintain milk quality, particularly fat content, which is crucial in dairy markets. The data support theoretical models that position herd size as a key productivity factor, as noted by
Allore et al., (1997). Larger herds benefit from economies of scale, improving feeding, veterinary care and environmental control. Selective breeding in larger herds enhances traits like heat stress resilience, critical in semi-arid areas like Souss-Massa
(Vries et al., 2014) and supports improved herd health and sustainability (
Neethirajan, 2024). However, larger herds present challenges for animal welfare, with higher disease rates, lameness and mastitis due to crowded housing and limited movement
(Garber et al., 1994; Keyserlingk et al., 2012). These issues can be mitigated through welfare-focused management, such as rotational grazing and enriched environments.
For dairy farms in semi-arid regions, cooling systems and shade structures are vital to reduce thermal stress, which impacts both productivity and welfare.
Miciñsk and Pogorzelska (2010) recommend misting and shading systems to preserve milk yield and fat content during peak summer months. In regions like Souss-Massa, where high temperatures challenge dairy operations, these cooling systems are essential. Additionally, tailored nutritional regimes for high-yield cows are crucial. Structured feeding approaches that optimize milk output without compromising quality or health are necessary. Balanced nutrition programs, emphasizing forage quality and high-protein concentrates
(Smith et al., 1997), can enhance both milk composition and overall yield. These adjustments support sustainable dairy farming, improving productivity while managing environmental constraints.
Intensive farming with large herds boosts productivity but raises concerns about long-term sustainability and animal welfare. Studies show a strong link between large herd sizes and increased disease incidence, particularly mastitis and lameness, which affect milk yield and quality
(Barkema et al., 2009). Lievaart et al., (2007) found that close physical proximity and poor ventilation in large herds exacerbate disease spread, especially in hot climates. Balancing productivity and animal welfare is essential, as seen in welfare-oriented dairy farming practices in the U.S.A and Netherlands.
Garber et al., (1994) and
Trotz-Williams et al. (2008) advocate for regular health monitoring, sufficient space and reduced density to address welfare challenges. Integrating welfare into herd management helps sustain long-term productivity and animal health, which is critical, as poor welfare leads to higher culling rates and decreased reproductive efficiency (
De Vries et al., 2020).
The study suggests that dairy farms in semi-arid climates can increase productivity by optimizing herd size and implementing targeted management strategies. However, this must be balanced with animal welfare to ensure sustainability. Future research could explore the effectiveness of welfare interventions like cooling and nutritional adjustments in enhancing productivity without compromising health. Longitudinal studies could also provide insights into the long-term effects of intensive management on herd longevity, offering comprehensive models that consider productivity, welfare and economic viability over time (
Dinsmore, 2021). The relationship between herd size, productivity and welfare is complex, requiring careful management. As dairy farms in semi-arid regions expand, balancing these factors will be crucial for developing resilient, sustainable dairy production systems.
