Performance, behavior, and welfare of Friesian heifers housed in pens with 2, 4, and 8 individuals per concentrate feeding place

¹ Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain; Animal Nutrition, Management, and Welfare Research Group, Barcelona, Spain
² Unitat de Remugants-IRTA, 08140 Caldes de Montbui, Barcelona, Spain; Animal Nutrition, Management, and Welfare Research Group, Barcelona, Spain
³ Unitat de Remugants-IRTA, 08140 Caldes de Montbui, Barcelona, Spain; Animal Nutrition, Management, and Welfare Research Group, Barcelona, Spain; ICREA, Barcelona, Spain

^* To whom correspondence should be addressed. E-mail: Alfred.Ferret{at}uab.es.

	Abstract

The objective of the present study was to examine effects of increasing the number of heifers per concentrate feeding place on performance, behavior, welfare indicators, and ruminal fermentation of feedlot heifers. Seventy-two Friesian heifers were used in a factorial arrangement with 3 treatments and 3 blocks of similar BW. Treatments consisted of 2 (T2), 4 (T4), and 8 (T8) heifers per each place in the concentrate feeder (8 heifers/pen). Concentrate and straw were fed at 0830 in individual feeders and allowed ad libitum consumption. During 6 periods of 28 d each, DMI and ADG were measured, and blood and rumen samples were taken. Fecal glucocorticoid metabolites and behavior were measured at periods 1, 3, and 6. Final BW, ADG, and G:F ratio were not affected by treatments. Variability in final BW between heifers sharing the same pen tended to increase (P = 0.06) and concentrate intake decreased linearly as competition increased. The proportion of abscessed livers responded quadratically, being 8, 4, and 20% for T2, T4, and T8, respectively. Concentrate eating time decreased (P = 0.001) and eating rate increased (P = 0.05) linearly, whereas the variability between pen-mates in concentrate eating time was greatest in T4 and T8. Increasing competition resulted in a quadratic response (P = 0.02) in daily lying time (greatest in T2), whereas standing time increased linearly (P = 0.02). The number of displacements among pen-mates from the concentrate feeders, as well as the total sum of displacements, increased linearly (P < 0.05) with increasing competition. The pen-average of fecal glucocorticoid metabolites was not affected by treatments (P 0.16) but the pen's maximum concentration responded quadratically (P < 0.001), being greatest in T8, and dominant heifers being the most affected. Serum haptoglobin concentration increased linearly (P = 0.05) with competition, particularly within the most subordinate heifers. Increased competition reduced (P < 0.05) ruminal pH only in periods 1 and 2 and increased ruminal lactate (P = 0.02). Increasing competition at the concentrate feeders increased the variability in final BW but performance was not affected. Detrimental effects on animal welfare might be deduced from the altered feeding behavior, reduced resting time, and increased aggression. Ruminal lactate and blood haptoglobin indicate that the risk of rumen acidosis might increase with competition whereas liver abscesses increased at 8 heifers per feeder.

Key Words: behavior, competition, heifers, ruminal acidosis, welfare