Exploring the Influence of Parity on Metabolic Profile, Performance and Offspring Growth in Bos indicus Beef Cows

The objective of this study was to evaluate how parity (primiparous vs. multiparous) influences metabolic profile, performance, and offspring growth in grazing Nellore cows, and to explore potential associations among key metabolic traits, milk yield, and performance indicators. Thirty-four pregnant Nellore cows at approximately 230 ± 20 days of gestation were sorted by parity group and randomly allocated into one of six <i>Uruchloa decumbens</i> pastures, totaling 17 multiparous cows (597.8 ± 39 kg; age = 4 to 6 yrs) and 17 primiparous cows (407 ± 33 kg, age = 2 to 3 yrs). Considering calving day as day 0, cow full BW and BCS were collected on days -63, -21, -7, 0, 7, 21, 63, 91, 140 and 203. Cow blood samples were collected on days -21, -14, -7, 0, 7, 14, 21, 42, 63, 91, 140 and 203. Milk yield was measured in the following day after all blood collections. Primiparous cows had higher glucose on days -7 and 0 (<i>p</i> = 0.04), greater NEFA concentration from -14 to 63 days (<i>p</i> < 0.001), and lower IGF-1 concentration from days 7 to 42 but higher on days 140 and 203 (<i>p</i> < 0.001). They also exhibited lower total proteins, albumin, and globulins, but higher serum urea N concentration (<i>p</i> < 0.001). Primiparous cows also had lower milk yield (<i>p</i> = 0.02), calf birth (<i>p</i> = 0.02) and weaning weights (<i>p</i> = 0.01) compared with multiparous cows. Pearson correlation analysis revealed distinct metabolic and physiological interrelationships across gestational and lactational stages in multiparous and primiparous cows. Overall, multiparous cows showed a less catabolic metabolic profile during the periparturient period to lactation. Primiparous cows experienced a more intense mobilization of body reserves during the early lactation period, but a more positive nutritional status towards late lactation, evidenced by recovery of IGF-1 levels and body weight gain.