# Effect of increasing prickly pear cactus (Nopalea cochenillifera) levels in diets of Holstein × Zebu dairy cows on nutrients intake and digestibility, ingestive behavior, and milk fatty acids profile

## TL;DR

This study found that adding prickly pear cactus to dairy cow diets can change nutrient intake, digestion, and milk fat composition, with optimal results at moderate inclusion levels.

## Contribution

The novel contribution is identifying optimal prickly pear cactus inclusion levels for dairy cows under tropical conditions to maintain milk production while improving nutrient utilization.

## Key findings

- Inclusion of prickly pear cactus reduced neutral detergent fiber and water intake in dairy cows.
- Milk fatty acid profile changed with reduced CLA c9t11 and n-3 fatty acids, and increased saturated fatty acids.
- Intermediate levels of prickly pear cactus (32–35% of dry matter) optimized nutrient utilization without affecting milk yield.

## Abstract

This study evaluated the effects of including different levels of prickly pear cactus (Nopalea cochenillifera) in the diets of crossbred dairy cows (Holstein × Zebu) on nutrient intake and digestibility, nitrogen balance, microbial protein synthesis, milk yield and composition, and feeding behavior. Eight multiparous cows (15.9 ± 1.8 kg/day of milk; 100 ± 11 days in milk, mean ± SD) were assigned to a double 4 × 4 Latin square design with 21-day periods, consisting of 16 days of dietary adaptation followed by 5 days of data collection. The experimental diets were: (1) CON, without prickly pear cactus (PPC); (2) PPC16, containing 16% PPC in dry matter (DM); (3) PPC32, with 32% PPC in DM; and (4) PPC48, with 48% PPC in DM. The inclusion of PPC reduced NDF intake, both in absolute terms (P = 0.037) and relative to body weight (P = 0.021), and decreased water intake compared with the control diet (P < 0.001), showing a quadratic response to inclusion levels (P < 0.001). For digestibility, quadratic effects were observed for crude protein (P = 0.007) and ether extract (P < 0.001). Milk yield and principal components (protein, fat, and lactose) were not affected (P > 0.05). However, PPC reduced milk cholesterol concentration (P = 0.013) and altered the fatty acid profile, specifically decreasing CLA c9t11 (P = 0.025) and n-3 fatty acids (P = 0.033), while also increasing the proportion of saturated fatty acids (P = 0.027). It was concluded that intermediate levels of prickly pear cactus inclusion (32–35% of DM) optimized nutrient utilization while maintaining milk production, representing the most suitable supplementation strategy for crossbred dairy cows under tropical conditions.