Reproduction in Domestic Animals

214 MJR Paranhos da Costa, A Schmidek and LM Toledolosses (Cromberg and Paranhos da Costa 1997; Schmideket al. 2008).Cows usually isolate themselves from the herd whennear to calve. However, when they are in a smallpaddock, they are not able to do it, resulting in a higherrisk of fail or delay in the first suckling. This is because,under high density conditions, the social interactionsamong parturient cows are more frequent and sometimescalves spend time trying to suckle in other cowsthan in their own mothers (Ribeiro et al. 2004), justbecause these cows are close to the parturient cow andits respective calf, or because some cows show interesttowards a calf, behaving like its mother.Throughout the parturition process, cows usually lyedown and stand up just after delivering the calves(Paranhos da Costa and Cromberg 1998). The identificationof this simple behaviour has practical relevance, asthe risk of calf death is higher when the cow delivers in astanding (16.1%) rather than in a recumbent position(4.2%) (Paranhos da Costa et al. 2006b). Better understandingof this situation and its underlying factors mayassist to solve this problem. Some factors that affect thecows’ postures when delivering their calves were alreadyidentified, among them: lack of calving experience,presence of potential predators near the parturient cows(Toledo 2005; Paranhos da Costa 2008).The episodes of aggressive behaviour towards anewborn calf are also important. According to Schmideket al. (2006), they were more frequent in primiparousthan in multiparous cows (55.7% and 22.0%,respectively), resulting on higher frequency of calvesthat did not succeed to suckle after 3 h after birth(15.7% and 5.7%, respectively) and higher latency forfirst suckling (102.6 and 76.0 min, respectively). The riskof calf mortality also increase with the delay in the firstsuckling latency above 3 h (Schmidek et al. 2006), andby this, we recommend the need of reviewing the criticallimit for the cattle first suckling latency, usually reportedas 6 h after calving (Broom 1983).The presence of potential predators in the calvingplace also affects the mother–young relationship. Underour environmental conditions, special attention wasgiven to the black vultures (Coragyps atratus) becausethis species is more and more present at the cattlecalving places, disturbing the formation of the mother–offspring bond and attacking directly the calves. Themain effect of the presence of black vulture was todecrease the time that the cows spend in contact withtheir calves, as usually they spend more time invigilance. This situation resulted in negative effects onthe latencies to stand up and first suckling (Toledo2005).Weather conditions (Toledo et al. 2007), calf weightat birth, udder shape and teat size (Ventrop andMichanek 1992) are other identified factors that wouldresult in fail or delay in the first suckling.Failure in the first suckling increases the mortality rate ofcalvesIn animal husbandry, this subject has crucial importancebecause the death of one animal means an economicalloss (Cromberg and Paranhos da Costa 1997).It is expected that cow–calf behaviour during the firsthours after calving has a direct effect on the calfmortality; by this, the knowledge of the mother–offspring behaviour has practical significance, becauseit can be used to evaluate the strategies of managementand selection in beef cattle. In spite of this, there are notmuch data about this subject, especially when consideringcattle bred in Brazil.In one of our studies (Schmidek et al. 2008), the highpercentage of newborn Guzerat calves that fail in thefirst suckling stimulated us to study the genetic andenvironmental factors underlying this situation, and itseffect on calf mortality. Data from 1527 calves (bornbetween 1992 and 2004) revealed that 279 (18.3%) ofthem failed in first suckling and were helped to suckle,more than 6 h after birth. Two major factors wereidentified for the occurrence of the failure in the firstsuckling: cows with big udders or teats and calvesweighing less than 25 kg at birth. The risk of death forcalves that failed in the first suckling was 28% timeshigher (p < 0.01) than those that were able to suckle ontime. The estimated maternal effect presented lowheritability (0.08) and the correspondent direct effectwas null. These low heritability estimates indicate thatthe genetic progress through selection criteria againstfailure of the first suckling might be achieved only inlong term. However, the conformation of the udder andthe birth weight of the calf are two possible indicatorsfor immediate action to help the calf to suckle as soon aspossible.Routine inspections in the maternity area to detecteventual problems with parturient cows and neonates(ideally three times in the day: early morning, noon andlate afternoon) could minimize the incidence of thefailure in the first suckling of newborn calves (Paranhosda Costa 2008; Schmidek et al. 2008).Variability in the expression of cow and calf behavioursamong and within breedsThe differences in suckling behaviour seem to beproduced by a complex combination of genetic andenvironmental factors, which would result in a particularbehavioural relationship style of a mother–offspringpair (Paranhos da Costa et al. 2006a). There arescientific evidences of variability among Zebu breeds,among herds of the same breed and among individualswithin herd; for example, the latency to stand up afterparturition varied significantly between Nelore andGuzerat breed (Paranhos da Costa and Cromberg1998), between two herds of Nelore breed (Toledo et al.2007) and among several progenies of Nelore bulls(Schmidek 2003).It is usually accepted that the behavioural variationbetween species, breeds, populations and individuals hasa genetic bases, by this, the most common strategy toidentify genetic variability in behaviour is the comparisonamong breeds (Hohenboken 1986; Buchenauer1999). For example, the variation in maternal behaviourbetween beef and dairy cows was reported (Le Neindre1989; Buchenauer 1999), showing that beef cowsdisplayed better maternal behaviour than dairy cows.Besides, beef calves are usually more agile to stand upÓ 2008 The Authors. Journal compilation Ó 2008 Blackwell Verlag